Showing posts with label TRANSALKYLATION. Show all posts
Showing posts with label TRANSALKYLATION. Show all posts
Tuesday, July 5, 2016
Transalkylation Process (ExxonMobil)
CATEGORY: TRANSALKYLATION
Transalkylation Process (ExxonMobil)
United States Patent Application 20160176787
Molinier; Michel ; et al. June 23, 2016
Applicant: ExxonMobil Chemical Patents Inc.
Abstract
Disclosed is a transalkylation process for making an aromatic material between a light aromatic material and a heavier aromatic material in the presence of hydrogen and a transalkylation catalyst comprising a hydrogenation component and a transalkylation component. The process comprises conducting the transalkylation reaction under conditions conducive to reducing the amount of cyclic compounds in the transalkylation reaction mixture in the beginning phase of the operation that is different from the conditions after the beginning phase. The invention is useful, e.g., in transalkylation between toluene and C9+ aromatic feed materials to produce xylenes and/or benzene.
TECHNICAL FIELD
[0002] This invention relates to a transalkylation process for making an aromatic material. In particular, the present invention relates to a transalkylation process between benzene/toluene and heavier aromatic materials. The present invention is useful, e.g., in making xylenes and/or benzene from toluene and aromatic materials comprising nine or more carbon atoms.
BACKGROUND
[0003] A source of benzene and xylene is catalytic reformate, which is prepared by contacting a mixture of petroleum naphtha and hydrogen with a strong hydrogenation/dehydrogenation catalyst, such as platinum, on a moderately acidic support, such as a halogen-treated alumina. Usually, a six carbon (C6) to eight carbon (C8) fraction is separated from the reformate and extracted with a solvent selective for aromatics or aliphatics to produce a mixture of aromatic materials that is relatively free of aliphatics. This mixture of aromatic materials usually contains benzene, toluene and xylenes (BTX), along with ethylbenzene.
[0004] Refineries have also focused on the production of benzene and xylene by transalkylation of an aromatic having nine or more carbons (C9+A) and toluene over noble metal-containing zeolite catalysts. During the transalkylation of C9+A and toluene to high value petrochemical products, such as benzene and xylene, over catalysts containing noble metals, by-products, such as saturated materials, are typically produced in the process. These by-products can boil in the same temperature range as the desired aromatic products, making separation of the desired products at high purity levels difficult. For example, a commercial benzene product may need a purity of 99.85 wt % or higher. However, initial benzene purity after distillation of a transalkylation reaction product is typically only 99.2% to 99.5% due to the presence of coboilers, such as methylcyclopentane, cyclohexane, 2,3-dimethylpentane, dimethylcyclopentane and 3-methylhexane. Therefore, an additional extraction step is usually required to further improve benzene product purity to the desired level.
[0005] One solution to the problem of the production of benzene co-boilers during the transalkylation of heavy aromatics is disclosed in U.S. Pat. No. 5,942,651 and involves the steps of contacting a feed comprising C9+A materials and toluene under transalkylation reaction conditions with a first catalyst composition comprising a zeolite having a constraint index ranging from 0.5 to 3, such as ZSM-12, and a hydrogenation component. The effluent resulting from the first contacting step is then contacted with a second catalyst composition which comprises a zeolite having a constraint index ranging from 3 to 12, such as ZSM-5, and which may be in a separate bed or a separate reactor from the first catalyst composition to produce a transalkylation reaction product comprising benzene and xylene. A benzene to product having a purity of at least 99.85% may be obtained by distilling the benzene from the transalkylation reaction product, without the need for an additional extraction step. According to the '651 patent, the second catalyst composition comprises up to 20 wt % of the total weight of the first and second catalyst compositions.
[0006] U.S. Pat. No. 5,905,051 discloses a process for converting a hydrocarbon stream such as, for example, a C9+A materials to C6 to C8 aromatic hydrocarbons, such as xylenes, by contacting the stream with a catalyst system comprising a first catalyst composition and a second catalyst composition, wherein said catalyst compositions are present in separate stages and are not physically mixed or blended and wherein said first catalyst composition is a metal-promoted, alumina- or silica-bound zeolite beta, and said second catalyst composition is ZSM-5 having incorporated therein an activity promoter selected from the group consisting of silicon, phosphorus, sulfur, and combinations thereof. According to the '051 patent, the use of the separate catalytic stages improves the conversion of C9+A materials and naphthalenes to xylenes and decreases the amount of undesirable ethylbenzene in the product.
[0007] U.S. Pat. No. 5,030,787 discloses an improved disproportionation/transalkylation process. The improved process of this invention is conducted such that transalkylation of a C9+A feedstock, or disproportionation of a feedstock containing toluene and C9+A(s), is carried out in the vapor-phase by containing said feedstock in a reaction zone with a catalyst comprising a zeolite possessing a Constraint Index, as defined below, of from 1 to about 3 and preferably which has been hydrogen, hydrogen precursor and/or non-noble Group VIII metal exchanged, thermally treated and/or hydrothermally treated, under conditions effective to convert such feedstock to a product containing substantial quantities of C6-C8 aromatic materials, e.g., benzene and xylene(s), especially the latter. The product effluent is separated and distilled to remove the desired products. If desired, any unreacted material(s), e.g., toluene and/or C9+ material, can be recycled.
[0008] U.S. Pat. No. 5,030,787 discloses a transalkylation process to convert a heavy aromatics feed to lighter aromatics products, such as benzene, toluene and xylenes by contacting a C9+A fraction and benzene and/or toluene over a catalyst comprising a zeolite, such as ZSM-12, and a hydrogenation component, preferably platinum. The catalyst, with hydrogenation component, is treated to reduce aromatics loss. Treatment includes exposure to steam and/or sulfur after incorporation of the hydrogenation component. For additional stability and aromatics retention, the steamed and/or sulfur treated catalyst is sulfided by cofeeding a source of sulfur. In a further embodiment of the invention, a low hydrogen partial pressure is employed to retain aromatics.
[0009] U.S. Pat. No. 7,663,010 discloses a catalyst system adapted for transalkylation of a C9+ aromatic material (C9+A) feedstock with a C6 aromatic material (C6A) and/or C7 aromatic material (C7A) feedstock, comprising: (a) a first catalyst comprising a first molecular sieve having a Constraint Index in the range of 3-12 and 0.01 to 5 wt % of at least one source of a first metal element of Groups 6-10; and (b) a second catalyst comprising a second molecular sieve having a Constraint Index less than 3 and 0 to 5 wt % of at least one source of a second metal element of Groups 6-10, wherein the weight ratio of the first catalyst over the second catalyst is in the range of 5:95 to 75:25, and wherein the first catalyst is located in front of the second catalyst when they are brought into contact with the C9+A feedstock and the C6A and/or C7A feedstock in the presence of hydrogen. According to this patent, the catalyst system has improved aging rates and enables transalkylation at a high throughput.
SUMMARY
[0010] It has been found that in transalkylation reaction processes using a catalyst comprising a transalkylation component and a hydrogenation metal component in the presence of hydrogen, hydrogenation of aromatic rings can occur resulting in the production of non-negligible amount of alicyclic compounds. It is highly desirable the amount of such alicyclic compounds is reduced in the transalkylation product mixture. It has been found that by conducting the transalkylation reaction process under a set of conditions in the beginning phase of the reaction process different from the set of conditions in the subsequent operation, one can significantly reduce the overall formation of alicyclic compounds in the process.
[0011] Accordingly, the present invention provides a transalkylation process comprising conducting a transalkylation reaction between a C6A material and/or C7A material hydrocarbon with a nine carbon aromatic material (C9A) and/or ten carbon aromatic material (C10A) hydrocarbon in a transalkylation reactor in the presence of a transalkylation catalyst comprising a transalkylation component and a hydrogenation metal component under transalkylation conditions, the process comprising: (i) conducting the transalkylation reaction under a first set of transalkylation conditions in the beginning phase of the operation cycle; and (ii) conducting the transalkylation reaction under a second set of transalkylation conditions differing from the first set of transalkylation conditions after the beginning phase of the operation cycle; such that the amount of alicyclic compounds in the transalkylation product mixture in the beginning phase is reduced compared to conducting the transalkylation reaction under the second set of transalkylation conditions in the beginning phase.
Free Full Text Source: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=8&f=G&l=50&co1=OR&d=PG01&s1=exxonmobil.AS.&s2=exxonmobil.AANM.&OS=AN/exxonmobil+OR+AANM/exxonmobil&RS=AN/exxonmobil+OR+AANM/exxonmobil
Wednesday, February 19, 2014
Aromatic transalkylation using UZM-44 aluminosilicate zeolite (UOP)
CATEGORY: TRANSALKYLATION
PATENT
Aromatic transalkylation using UZM-44 aluminosilicate zeolite (UOP)
Publication Number Us8609921 B1
Publication Type Grant
Application Number Us 13/792,667
Publication Date Dec 17, 2013
Inventors
Christopher P. Nicholas, Edwin P. Boldingh, Marc R. Schreier
Original Assignee
Uop Llc
Abstract
A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula NanMm k+TtAl1-xExSiyOz where M represents a metal or metals from zine, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, “m” is the mole ratio of M to (Al+E), T is the organic structure directing agent or agents, and E is a framework element such as gallium. UZM-44 may be used to catalyze a process for the transalkylation of a feedstream comprising one or more of C7, C9, C10 and C11+ aromatics to obtain a transalkylation product stream having an increased concentration of C8 aromatics relative to that of the feedstream.
FIELD OF THE INVENTION
This invention relates to a new family of aluminosilicate zeolites designated UZM-44 as the catalytic composite for aromatic transalkylation reactions. They are represented by the empirical formula of:
NanMm k+TtAl1-xExSiyOz
where M represents a metal or metals from zinc or Group 1 (IUPAC 1), Group 2 (IUPAC 2), Group 3 (IUPAC 3) or the lanthanide series of the periodic table, T is the organic directing agent or agents derived from reactants R and Q where R is an A,Ω-dihalosubstituted alkane such as 1,5-dibromopentane and Q is at least one neutral amine having 6 or fewer carbon atoms such as 1-methylpyrrolidine. E is a framework element such as gallium.
BACKGROUND OF THE INVENTION
Zeolites are crystalline aluminosilicate compositions which are microporous and which are formed from corner sharing AlO2 and SiO2 tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared, are used in various industrial processes. Synthetic zeolites are prepared via hydrothermal synthesis employing suitable sources of Si, Al and structure directing agents such as alkali metals, alkaline earth metals, amines, or organoammonium cations. The structure directing agents reside in the pores of the zeolite and are largely responsible for the particular structure that is ultimately formed. These species balance the framework charge associated with aluminum and can also serve as space fillers. Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity, and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent zeolite crystal structure. Zeolites can be used as catalysts for hydrocarbon conversion reactions, which can take place on outside surfaces as well as on internal surfaces within the pore.
A particular zeolite, IM-5, was first disclosed by Benazzi, et al. in 1996 (FR96/12873; WO98/17581) who describe the synthesis of IM-5 from the flexible dicationic structure directing agent, 1,5-bis(N-methylpyrrolidinium)pentane dibromide or 1,6-bis(N-methylpyrrolidinium)hexane dibromide in the presence of sodium. After the structure of IM-5 was solved by Baerlocher et al. (Science, 2007, 315, 113-6), the International Zeolite Structure Commission gave the code of IMF to this zeolite structure type, see Atlas of Zeolite Framework Types. The IMF structure type was found to contain three mutually orthogonal sets of channels in which each channel is defined by a 10-membered ring of tetrahedrally coordinated atoms, however, connectivity in the third dimension is interrupted every 2.5 nm, therefore diffusion is somewhat limited. In addition, multiple different sizes of 10-membered ring channels exist in the structure.
Applicants have successfully prepared a new family of materials designated UZM-44. The topology of the materials is similar to that observed for IM-5. The materials are prepared via the use of a mixture of simple commercially available structure directing agents, such as 1,5-dibromopentane and 1-methylpyrrolidine. UZM-44 may be used as a catalyst in aromatic transalkylation reactions.
SUMMARY OF THE INVENTION
As stated, the present invention relates to using a new catalytic composite comprising a new aluminosilicate zeolite designated UZM-44 in a process for aromatic transalkylation. Accordingly, one embodiment of the invention is a material having a three-dimensional framework of at least AlO2 and SiO2 tetrahedral units and an empirical composition in the as synthesized and anhydrous basis expressed by an empirical formula of:
NanMm k+TtAl1-xExSiyOz
where “n” is the mole ratio of Na to (Al+E) and has a value from approximately 0.05 to 0.5, M represents at least one metal selected from the group consisting of zinc, Group 1 (IUPAC 1), Group 2 (IUPAC 2), Group 3 (IUPAC 3), and the lanthanide series of the periodic table, and any combination thereof, “m” is the mole ratio of M to (Al+E) and has a value from 0 to 0.5, “k” is the average charge of the metal or metals M, T is the organic structure directing agent or agents derived from reactants R and Q where R is an A,Ω-dihalogen substituted alkane having 5 carbon atoms and Q is at least one neutral monoamine having 6 or fewer carbon atoms, “t” is the mole ratio of N from the organic structure directing agent or agents to (Al+E) and has a value of from about 0.5 to about 1.5, E is an element selected from the group consisting of gallium, iron, boron and combinations thereof, “x” is the mole fraction of E and has a value from 0 to about 1.0, “y” is the mole ratio of Si to (Al+E) and varies from greater than 9 to about 25 and “z” is the mole ratio of 0 to (Al+E) and has a value determined by the equation:
z=(n+k·m+3+4·y)/2
Another embodiment of the catalytic composite of the invention is a microporous crystalline zeolite having a three-dimensional framework of at least AlO2 and SiO2 tetrahedral units and an empirical composition in the as synthesized and anhydrous basis expressed by an empirical formula of:
NanMm k+TtAl1-xExSiyOz
where “n” is the mole ratio of Na to (Al+E) and has a value from approximately 0.05 to 0.5, M represents a metal or metals from Group 1 (IUPAC 1), Group 2 (IUPAC 2), Group 3 (IUPAC 3), the lanthanide series of the periodic table or zinc, “m” is the mole ratio of M to (Al+E) and has a value from 0 to 0.5, “k” is the average charge of the metal or metals M, T is the organic structure directing agent or agents derived from reactants R and Q where R is an AP-dihalogen substituted alkane having 5 carbon atoms and Q is at least one neutral monoamine having 6 or fewer carbon atoms, “t” is the mole ratio of N from the organic structure directing agent or agents to (Al+E) and has a value of from 0.5 to 1.5, E is an element selected from the group consisting of gallium, iron, boron and combinations thereof, “x” is the mole fraction of E and has a value from 0 to about 1.0, “y” is the mole ratio of Si to (Al+E) and varies from greater than 9 to about 25 and “z” is the mole ratio of O to (Al+E) and has a value determined by the equation:
z=(n+k·m+3+4·y)/2
and the zeolite is characterized in that it has the x-ray diffraction pattern having at least the d-spacings and intensities set forth in Table A. The zeolite is thermally stable up to a temperature of greater than 600° C. in one embodiment and at least 800° C. in another embodiment.
The catalytic composite of the invention may be prepared by a process comprising forming a reaction mixture containing reactive sources of Na, R, Q, Al, Si and optionally E and/or M and heating the reaction mixture at a temperature of about 160° C. to about 180° C., or about 165° C. to about 175° C., for a time sufficient to form the zeolite. The reaction mixture has a composition expressed in terms of mole ratios of the oxides of:
a-bNa2O:bMn/2O:cRO:dQ:1-eAl2O3 :eE2O3 :fSiO2 :gH2O
where “a” has a value of about 10 to about 30, “b” has a value of 0 to about 30, “c” has a value of about 1 to about 10, “d” has a value of about 2 to about 30, “e” has a value of 0 to about 1.0, “f′ has a value of about 30 to about 100, “g” has a value of about 100 to about 4000. With this number of reactive reagent sources, many orders of addition can be envisioned. Typically, the aluminum reagent is dissolved in the sodium hydroxide prior to adding the silica reagents. Reagents R and Q can be added together or separately in many different orders of addition.
The invention uses UZM-44 as the catalyst or a catalyst component in a process for the transalkylation of alkylaromatic hydrocarbons. Accordingly, a broad embodiment of the present invention is a process for transalkylation of a feedstream comprising one or more of C7, C9, C10 and C11+ aromatics to obtain a transalkylation product stream having an increased concentration of C8 aromatics relative to that of the feedstream, comprising contacting the feedstream at transalkylation conditions with a catalyst comprising UZM-44.
Free Full Text Source: https://www.google.com/patents/US8609921?dq=hydrogen+inassignee:uop&hl=en&sa=X&ei=C7rvUo_7FInmyQHx1YCgDw&ved=0CEEQ6AEwAjgU
PATENT
Aromatic transalkylation using UZM-44 aluminosilicate zeolite (UOP)
Publication Number Us8609921 B1
Publication Type Grant
Application Number Us 13/792,667
Publication Date Dec 17, 2013
Inventors
Christopher P. Nicholas, Edwin P. Boldingh, Marc R. Schreier
Original Assignee
Uop Llc
Abstract
A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula NanMm k+TtAl1-xExSiyOz where M represents a metal or metals from zine, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, “m” is the mole ratio of M to (Al+E), T is the organic structure directing agent or agents, and E is a framework element such as gallium. UZM-44 may be used to catalyze a process for the transalkylation of a feedstream comprising one or more of C7, C9, C10 and C11+ aromatics to obtain a transalkylation product stream having an increased concentration of C8 aromatics relative to that of the feedstream.
FIELD OF THE INVENTION
This invention relates to a new family of aluminosilicate zeolites designated UZM-44 as the catalytic composite for aromatic transalkylation reactions. They are represented by the empirical formula of:
NanMm k+TtAl1-xExSiyOz
where M represents a metal or metals from zinc or Group 1 (IUPAC 1), Group 2 (IUPAC 2), Group 3 (IUPAC 3) or the lanthanide series of the periodic table, T is the organic directing agent or agents derived from reactants R and Q where R is an A,Ω-dihalosubstituted alkane such as 1,5-dibromopentane and Q is at least one neutral amine having 6 or fewer carbon atoms such as 1-methylpyrrolidine. E is a framework element such as gallium.
BACKGROUND OF THE INVENTION
Zeolites are crystalline aluminosilicate compositions which are microporous and which are formed from corner sharing AlO2 and SiO2 tetrahedra. Numerous zeolites, both naturally occurring and synthetically prepared, are used in various industrial processes. Synthetic zeolites are prepared via hydrothermal synthesis employing suitable sources of Si, Al and structure directing agents such as alkali metals, alkaline earth metals, amines, or organoammonium cations. The structure directing agents reside in the pores of the zeolite and are largely responsible for the particular structure that is ultimately formed. These species balance the framework charge associated with aluminum and can also serve as space fillers. Zeolites are characterized by having pore openings of uniform dimensions, having a significant ion exchange capacity, and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent zeolite crystal structure. Zeolites can be used as catalysts for hydrocarbon conversion reactions, which can take place on outside surfaces as well as on internal surfaces within the pore.
A particular zeolite, IM-5, was first disclosed by Benazzi, et al. in 1996 (FR96/12873; WO98/17581) who describe the synthesis of IM-5 from the flexible dicationic structure directing agent, 1,5-bis(N-methylpyrrolidinium)pentane dibromide or 1,6-bis(N-methylpyrrolidinium)hexane dibromide in the presence of sodium. After the structure of IM-5 was solved by Baerlocher et al. (Science, 2007, 315, 113-6), the International Zeolite Structure Commission gave the code of IMF to this zeolite structure type, see Atlas of Zeolite Framework Types. The IMF structure type was found to contain three mutually orthogonal sets of channels in which each channel is defined by a 10-membered ring of tetrahedrally coordinated atoms, however, connectivity in the third dimension is interrupted every 2.5 nm, therefore diffusion is somewhat limited. In addition, multiple different sizes of 10-membered ring channels exist in the structure.
Applicants have successfully prepared a new family of materials designated UZM-44. The topology of the materials is similar to that observed for IM-5. The materials are prepared via the use of a mixture of simple commercially available structure directing agents, such as 1,5-dibromopentane and 1-methylpyrrolidine. UZM-44 may be used as a catalyst in aromatic transalkylation reactions.
SUMMARY OF THE INVENTION
As stated, the present invention relates to using a new catalytic composite comprising a new aluminosilicate zeolite designated UZM-44 in a process for aromatic transalkylation. Accordingly, one embodiment of the invention is a material having a three-dimensional framework of at least AlO2 and SiO2 tetrahedral units and an empirical composition in the as synthesized and anhydrous basis expressed by an empirical formula of:
NanMm k+TtAl1-xExSiyOz
where “n” is the mole ratio of Na to (Al+E) and has a value from approximately 0.05 to 0.5, M represents at least one metal selected from the group consisting of zinc, Group 1 (IUPAC 1), Group 2 (IUPAC 2), Group 3 (IUPAC 3), and the lanthanide series of the periodic table, and any combination thereof, “m” is the mole ratio of M to (Al+E) and has a value from 0 to 0.5, “k” is the average charge of the metal or metals M, T is the organic structure directing agent or agents derived from reactants R and Q where R is an A,Ω-dihalogen substituted alkane having 5 carbon atoms and Q is at least one neutral monoamine having 6 or fewer carbon atoms, “t” is the mole ratio of N from the organic structure directing agent or agents to (Al+E) and has a value of from about 0.5 to about 1.5, E is an element selected from the group consisting of gallium, iron, boron and combinations thereof, “x” is the mole fraction of E and has a value from 0 to about 1.0, “y” is the mole ratio of Si to (Al+E) and varies from greater than 9 to about 25 and “z” is the mole ratio of 0 to (Al+E) and has a value determined by the equation:
z=(n+k·m+3+4·y)/2
Another embodiment of the catalytic composite of the invention is a microporous crystalline zeolite having a three-dimensional framework of at least AlO2 and SiO2 tetrahedral units and an empirical composition in the as synthesized and anhydrous basis expressed by an empirical formula of:
NanMm k+TtAl1-xExSiyOz
where “n” is the mole ratio of Na to (Al+E) and has a value from approximately 0.05 to 0.5, M represents a metal or metals from Group 1 (IUPAC 1), Group 2 (IUPAC 2), Group 3 (IUPAC 3), the lanthanide series of the periodic table or zinc, “m” is the mole ratio of M to (Al+E) and has a value from 0 to 0.5, “k” is the average charge of the metal or metals M, T is the organic structure directing agent or agents derived from reactants R and Q where R is an AP-dihalogen substituted alkane having 5 carbon atoms and Q is at least one neutral monoamine having 6 or fewer carbon atoms, “t” is the mole ratio of N from the organic structure directing agent or agents to (Al+E) and has a value of from 0.5 to 1.5, E is an element selected from the group consisting of gallium, iron, boron and combinations thereof, “x” is the mole fraction of E and has a value from 0 to about 1.0, “y” is the mole ratio of Si to (Al+E) and varies from greater than 9 to about 25 and “z” is the mole ratio of O to (Al+E) and has a value determined by the equation:
z=(n+k·m+3+4·y)/2
and the zeolite is characterized in that it has the x-ray diffraction pattern having at least the d-spacings and intensities set forth in Table A. The zeolite is thermally stable up to a temperature of greater than 600° C. in one embodiment and at least 800° C. in another embodiment.
The catalytic composite of the invention may be prepared by a process comprising forming a reaction mixture containing reactive sources of Na, R, Q, Al, Si and optionally E and/or M and heating the reaction mixture at a temperature of about 160° C. to about 180° C., or about 165° C. to about 175° C., for a time sufficient to form the zeolite. The reaction mixture has a composition expressed in terms of mole ratios of the oxides of:
a-bNa2O:bMn/2O:cRO:dQ:1-eAl2O3 :eE2O3 :fSiO2 :gH2O
where “a” has a value of about 10 to about 30, “b” has a value of 0 to about 30, “c” has a value of about 1 to about 10, “d” has a value of about 2 to about 30, “e” has a value of 0 to about 1.0, “f′ has a value of about 30 to about 100, “g” has a value of about 100 to about 4000. With this number of reactive reagent sources, many orders of addition can be envisioned. Typically, the aluminum reagent is dissolved in the sodium hydroxide prior to adding the silica reagents. Reagents R and Q can be added together or separately in many different orders of addition.
The invention uses UZM-44 as the catalyst or a catalyst component in a process for the transalkylation of alkylaromatic hydrocarbons. Accordingly, a broad embodiment of the present invention is a process for transalkylation of a feedstream comprising one or more of C7, C9, C10 and C11+ aromatics to obtain a transalkylation product stream having an increased concentration of C8 aromatics relative to that of the feedstream, comprising contacting the feedstream at transalkylation conditions with a catalyst comprising UZM-44.
Free Full Text Source: https://www.google.com/patents/US8609921?dq=hydrogen+inassignee:uop&hl=en&sa=X&ei=C7rvUo_7FInmyQHx1YCgDw&ved=0CEEQ6AEwAjgU
Monday, April 22, 2013
Process For Transalkylating Aromatic Hydrocarbons
CATEGORY: TRANSALKYLATION
PATENT
Process For Transalkylating Aromatic Hydrocarbons
Document Type and Number:
United States Patent Application 20130066123
Inventors:
Lafyatis, David S. (Schaumburg, IL, US)
Boldingh, Edwin P. (Arlington Heights, IL, US)
Baker, Eric J. (Chicago, IL, US)
Johnson, James A. (Clarendon Hills, IL, US)
Larson, Robert B. (Lisle, IL, US)
Application Number:
13/232019
Publication Date:
03/14/2013
Assignee:
UOP LLC (Des Plaines, IL, US)
Abstract:
The present invention is a process for transalkylating aromatic hydrocarbon compounds, the process comprising introducing an aromatic hydrocarbon feed stream into a transalkylation zone to yield high-purity benzene as a byproduct while meeting transalkylation objectives. The feed stream contacts a catalyst in the transalkylation zone under conditions adjusted to control benzene purity as well as transalkylation performance.
FIELD OF THE INVENTION
The present invention generally relates to improved processes for transalkylating aromatic hydrocarbon compounds. More particularly the invention relates to aromatic transalkylation processes producing xylenes and benzene.
DESCRIPTION OF RELATED ART
Xylene isomers (“xylenes”) and benzene are produced in large volumes from petroleum by the reforming of naphtha. However, neither the xylenes nor benzene are produced in sufficient volume to meet demand. Consequently, other hydrocarbons are necessarily converted to increase the yield of the xylenes and benzene via processes such as transalkylation, disproportionation, isomerization, and dealkylation. For example, toluene commonly is dealkylated to produce benzene. Alternatively, or additionally, toluene can be disproportionated to yield benzene and C8 aromatics from which the individual xylene isomers are recovered.
More recently, development has been directed at selectively transalkylating heavier aromatics, such as C9+ aromatics, with toluene and/or benzene to increase the yield of xylenes and benzene from aromatics complexes. In this regard, a variety of catalysts have been developed for these processes. For example, a wide range of zeolites, including mordenite, have been disclosed as effective transalkylation catalysts. Shaped catalysts, multiple zeolites, metal modifiers, and treatments such as steam calcination have been described as increasing the effectiveness of the catalysts.
Known catalysts are effective for producing xylenes and benzene. Specifically, catalysts having a sufficient metal function are suitable to convert heavier aromatics, such as C9+ aromatics to xylenes and benzene and provide improved catalyst stability in a transalkylation process. However, in transalkylation processes employing such catalysts, aromatic rings may become saturated or even cleaved resulting in naphthene and acyclic paraffin (non-aromatics) co-production, which can result in a loss of valuable aromatics. Also, because some of the non-aromatics have similar boiling points to benzene (benzene co-boilers), they are not readily removed to achieve a benzene product having a desired purity for commercial applications. Although the benzene co-boilers can be extracted with a solvent, such processes are expensive and typically require additional equipment.
Accordingly, it is desirable to provide a transalkylation process that produces a high-purity benzene product. Simultaineously, it is desirable to have a catalyst that exhibits a high activity and a strong resistance to coking so as to extend the time that the catalyst can be used before being replaced or regenerated. It furthermore would be highly desirable to be able to process very heavy feeds such as those containing the residual components as would come from unfractionated xylene column bottoms thereby further increasing xylene yield while still maintaining a high activity and a strong resistance to coking, so as to achieve a long catalyst life while achieving a high purity benzene product throughout the catalyst life. Catalysts that have the high stability and activity to attain a long catalyst life while processing heavy feeds such as those containing the residual components as would come from unfractionated xylene column bottoms under standard transalkylation conditions intrinsically will have difficulty in achieving high benzene purity at those same conditions early in its lifetime. Thus, a highly desirable feature of this invention is to provide an operating methodology that will allow all three aims of processing very heavy feed components whilst achieving a long catalyst lifetime and a high benzene purity throughout the entire run to be met. Thus, this invention provides a unique operating methodology to permit these aims to be met simultaneously.
Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims.
SUMMARY OF THE INVENTION
High activity and stability transalkylation catalysts such as proposed here for transalkylation tend to produce benzene co-boilers particularly during lower-severity conditions of normal operation during early portions of the process cycle, resulting in unacceptable benzene product purity. However, it has been discovered that initial operation during the early period of a process cycle at benzene-purity-directed conditions, whilst resulting in somewhat more rapid catalyst deactivation, also reduces the production of benzene co-boilers and better enables their destruction with concomitant enabling of acceptable purity of the benzene fraction of the transalkylation reaction product stream. The invention thus enables control of the amount of benzene co-boilers and the resulting purity of a benzene product stream recovered after distillation to separate the products during early parts of the process cycle, so that even high activity and stability transalkylation catalysts may meet benzene purity requirements.
In a broad embodiment, the invention is a process for transalkylating aromatic hydrocarbon compounds while maintaining the purity of a benzene product during an operating cycle comprising two or more portions of the cycle under differing transalkylation conditions, the process comprising: introducing a feed stream comprising the aromatic hydrocarbon compounds to a transalkylation zone containing a catalyst comprising an aluminosilicate zeolite component having an MOR framework type, optionally one or more additional aluminosilicate zeolite components, an inorganic oxide binder, and a metal component; contacting the feed stream with the catalyst in the transalkylation zone under benzene-purity-directed transalkylation conditions during an initial portion of the operating cycle; contacting the feed stream with the catalyst in the transalkylation zone under standard transalkylation conditions in a latter portion of the operating cycle; and, producing a reaction product stream comprising xylenes and a high-purity benzene fraction.
A more specific embodiment is a process for transalkylating aromatic hydrocarbon compounds while maintaining the purity of a benzene product during an operating cycle comprising two or more portions of the cycle under differing transalkylation conditions, the process comprising: introducing a feed stream comprising the aromatic hydrocarbon compounds to a transalkylation zone containing a catalyst comprising an aluminosilicate zeolite component having an MOR framework type, optionally one or more additional aluminosilicate zeolite components, an inorganic oxide binder, and a metal component; contacting the feed stream with the catalyst in the transalkylation zone during an initial portion of the operating cycle under benzene-purity-directed transalkylation conditions comprising one or more of higher operating temperature, lower operating pressure and lower hydrogen-to-hydrocarbon ratio relative to standard transalkylation conditions effective during a latter portion of the operating cycle; contacting the feed stream with the catalyst in the transalkylation zone under standard transalkylation conditions in the latter portion of the operating cycle; and, producing a reaction product stream comprising xylenes and a high-purity benzene fraction.
A yet more specific embodiment is a process for transalkylating aromatic hydrocarbon compounds while maintaining the purity of a benzene product during an operating cycle comprising two or more portions of the cycle under differing transalkylation conditions, the process comprising: introducing a feed stream comprising the aromatic hydrocarbon compounds to a transalkylation zone containing a catalyst comprising an aluminosilicate zeolite component having an MOR framework type, optionally one or more additional aluminosilicate zeolite components, an inorganic oxide binder, and a metal component; contacting the feed stream with the catalyst in the transalkylation zone during an initial portion of the operating cycle under benzene-purity-directed operating conditions comprising one or more of higher operating temperature, lower operating pressure and lower hydrogen-to-hydrocarbon ratio relative to standard transalkylation conditions effective during a latter portion of the operating cycle; transitioning the processing conditions gradually from benzene-purity-directed conditions to standard transalkylation conditions during the initial portion of the process cycle; contacting the feed stream with the catalyst in the transalkylation zone under standard transalkylation conditions in the latter portion of the operating cycle; and producing a reaction product stream comprising xylenes and a high-purity benzene fraction.
Benzene-purity-directed operating conditions are applied to produce a product stream that achieves a benzene purity of at least 99.9% benzene by distillation during an initial portion of the process cycle. Then, during the latter portion of the operating cycle after the catalyst has deactivated to a level where it can produce a product stream that achieves this benzene purity by mere fractionation at standard transalkylation conditions, reaction conditions are adjusted to milder conditions so that the lifetime of the catalyst may be maximized. Thus a satisfactory lifetime of the catalyst is maintained while producing a reaction product stream comprising xylenes and high-purity benzene over the entire process cycle.
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PATENT
Process For Transalkylating Aromatic Hydrocarbons
Document Type and Number:
United States Patent Application 20130066123
Inventors:
Lafyatis, David S. (Schaumburg, IL, US)
Boldingh, Edwin P. (Arlington Heights, IL, US)
Baker, Eric J. (Chicago, IL, US)
Johnson, James A. (Clarendon Hills, IL, US)
Larson, Robert B. (Lisle, IL, US)
Application Number:
13/232019
Publication Date:
03/14/2013
Assignee:
UOP LLC (Des Plaines, IL, US)
Abstract:
The present invention is a process for transalkylating aromatic hydrocarbon compounds, the process comprising introducing an aromatic hydrocarbon feed stream into a transalkylation zone to yield high-purity benzene as a byproduct while meeting transalkylation objectives. The feed stream contacts a catalyst in the transalkylation zone under conditions adjusted to control benzene purity as well as transalkylation performance.
FIELD OF THE INVENTION
The present invention generally relates to improved processes for transalkylating aromatic hydrocarbon compounds. More particularly the invention relates to aromatic transalkylation processes producing xylenes and benzene.
DESCRIPTION OF RELATED ART
Xylene isomers (“xylenes”) and benzene are produced in large volumes from petroleum by the reforming of naphtha. However, neither the xylenes nor benzene are produced in sufficient volume to meet demand. Consequently, other hydrocarbons are necessarily converted to increase the yield of the xylenes and benzene via processes such as transalkylation, disproportionation, isomerization, and dealkylation. For example, toluene commonly is dealkylated to produce benzene. Alternatively, or additionally, toluene can be disproportionated to yield benzene and C8 aromatics from which the individual xylene isomers are recovered.
More recently, development has been directed at selectively transalkylating heavier aromatics, such as C9+ aromatics, with toluene and/or benzene to increase the yield of xylenes and benzene from aromatics complexes. In this regard, a variety of catalysts have been developed for these processes. For example, a wide range of zeolites, including mordenite, have been disclosed as effective transalkylation catalysts. Shaped catalysts, multiple zeolites, metal modifiers, and treatments such as steam calcination have been described as increasing the effectiveness of the catalysts.
Known catalysts are effective for producing xylenes and benzene. Specifically, catalysts having a sufficient metal function are suitable to convert heavier aromatics, such as C9+ aromatics to xylenes and benzene and provide improved catalyst stability in a transalkylation process. However, in transalkylation processes employing such catalysts, aromatic rings may become saturated or even cleaved resulting in naphthene and acyclic paraffin (non-aromatics) co-production, which can result in a loss of valuable aromatics. Also, because some of the non-aromatics have similar boiling points to benzene (benzene co-boilers), they are not readily removed to achieve a benzene product having a desired purity for commercial applications. Although the benzene co-boilers can be extracted with a solvent, such processes are expensive and typically require additional equipment.
Accordingly, it is desirable to provide a transalkylation process that produces a high-purity benzene product. Simultaineously, it is desirable to have a catalyst that exhibits a high activity and a strong resistance to coking so as to extend the time that the catalyst can be used before being replaced or regenerated. It furthermore would be highly desirable to be able to process very heavy feeds such as those containing the residual components as would come from unfractionated xylene column bottoms thereby further increasing xylene yield while still maintaining a high activity and a strong resistance to coking, so as to achieve a long catalyst life while achieving a high purity benzene product throughout the catalyst life. Catalysts that have the high stability and activity to attain a long catalyst life while processing heavy feeds such as those containing the residual components as would come from unfractionated xylene column bottoms under standard transalkylation conditions intrinsically will have difficulty in achieving high benzene purity at those same conditions early in its lifetime. Thus, a highly desirable feature of this invention is to provide an operating methodology that will allow all three aims of processing very heavy feed components whilst achieving a long catalyst lifetime and a high benzene purity throughout the entire run to be met. Thus, this invention provides a unique operating methodology to permit these aims to be met simultaneously.
Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims.
SUMMARY OF THE INVENTION
High activity and stability transalkylation catalysts such as proposed here for transalkylation tend to produce benzene co-boilers particularly during lower-severity conditions of normal operation during early portions of the process cycle, resulting in unacceptable benzene product purity. However, it has been discovered that initial operation during the early period of a process cycle at benzene-purity-directed conditions, whilst resulting in somewhat more rapid catalyst deactivation, also reduces the production of benzene co-boilers and better enables their destruction with concomitant enabling of acceptable purity of the benzene fraction of the transalkylation reaction product stream. The invention thus enables control of the amount of benzene co-boilers and the resulting purity of a benzene product stream recovered after distillation to separate the products during early parts of the process cycle, so that even high activity and stability transalkylation catalysts may meet benzene purity requirements.
In a broad embodiment, the invention is a process for transalkylating aromatic hydrocarbon compounds while maintaining the purity of a benzene product during an operating cycle comprising two or more portions of the cycle under differing transalkylation conditions, the process comprising: introducing a feed stream comprising the aromatic hydrocarbon compounds to a transalkylation zone containing a catalyst comprising an aluminosilicate zeolite component having an MOR framework type, optionally one or more additional aluminosilicate zeolite components, an inorganic oxide binder, and a metal component; contacting the feed stream with the catalyst in the transalkylation zone under benzene-purity-directed transalkylation conditions during an initial portion of the operating cycle; contacting the feed stream with the catalyst in the transalkylation zone under standard transalkylation conditions in a latter portion of the operating cycle; and, producing a reaction product stream comprising xylenes and a high-purity benzene fraction.
A more specific embodiment is a process for transalkylating aromatic hydrocarbon compounds while maintaining the purity of a benzene product during an operating cycle comprising two or more portions of the cycle under differing transalkylation conditions, the process comprising: introducing a feed stream comprising the aromatic hydrocarbon compounds to a transalkylation zone containing a catalyst comprising an aluminosilicate zeolite component having an MOR framework type, optionally one or more additional aluminosilicate zeolite components, an inorganic oxide binder, and a metal component; contacting the feed stream with the catalyst in the transalkylation zone during an initial portion of the operating cycle under benzene-purity-directed transalkylation conditions comprising one or more of higher operating temperature, lower operating pressure and lower hydrogen-to-hydrocarbon ratio relative to standard transalkylation conditions effective during a latter portion of the operating cycle; contacting the feed stream with the catalyst in the transalkylation zone under standard transalkylation conditions in the latter portion of the operating cycle; and, producing a reaction product stream comprising xylenes and a high-purity benzene fraction.
A yet more specific embodiment is a process for transalkylating aromatic hydrocarbon compounds while maintaining the purity of a benzene product during an operating cycle comprising two or more portions of the cycle under differing transalkylation conditions, the process comprising: introducing a feed stream comprising the aromatic hydrocarbon compounds to a transalkylation zone containing a catalyst comprising an aluminosilicate zeolite component having an MOR framework type, optionally one or more additional aluminosilicate zeolite components, an inorganic oxide binder, and a metal component; contacting the feed stream with the catalyst in the transalkylation zone during an initial portion of the operating cycle under benzene-purity-directed operating conditions comprising one or more of higher operating temperature, lower operating pressure and lower hydrogen-to-hydrocarbon ratio relative to standard transalkylation conditions effective during a latter portion of the operating cycle; transitioning the processing conditions gradually from benzene-purity-directed conditions to standard transalkylation conditions during the initial portion of the process cycle; contacting the feed stream with the catalyst in the transalkylation zone under standard transalkylation conditions in the latter portion of the operating cycle; and producing a reaction product stream comprising xylenes and a high-purity benzene fraction.
Benzene-purity-directed operating conditions are applied to produce a product stream that achieves a benzene purity of at least 99.9% benzene by distillation during an initial portion of the process cycle. Then, during the latter portion of the operating cycle after the catalyst has deactivated to a level where it can produce a product stream that achieves this benzene purity by mere fractionation at standard transalkylation conditions, reaction conditions are adjusted to milder conditions so that the lifetime of the catalyst may be maximized. Thus a satisfactory lifetime of the catalyst is maintained while producing a reaction product stream comprising xylenes and high-purity benzene over the entire process cycle.
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