超临界条件下甲苯甲醇烷基化反应制对二甲苯的研究
摘要
SCF能溶解某些导致固体催化剂失活的物质、抑制催化剂失活。我们以反应物(主要是甲苯)作为超临界反应介质，以改性的ZSM-5沸石分子筛为催化剂，探讨在超临界条件下甲苯甲醇烷基化制对二甲苯反应性能及特点。
首先在常压下进行甲苯甲醇烷基化的研究，以找到用于超临界反应的催化剂。研究中对HZSM-5进行了水热、载镁、载磷、硅处理等改性处理。发现在没有载气的条件下，800℃水热处理的催化剂甲苯转化率为11％，对二甲苯选择性为66％。载Mg催化剂甲苯转化率为7％，对二甲苯选择性为93％。
在超临界条件下，超临界流体能够抑制催化剂积炭，延长催化剂寿命。对于800℃水热处理SZ催化剂，在460℃，常压反应条件下，甲苯转化率在20h后就会下降，而在460℃，5.5MPa条件下，甲苯转化率在46h内保持稳定。另外，对所选择的催化剂体系，与常压气相反应相比，超临界条件下的反应中，甲苯转化率提高，对二甲苯的选择性下降，但是也具有一定的选择性。从而认为：在超临界条件下的反应中，超临界流体能萃取积炭前体、抑制催化剂失活；甲苯转化率提高，但对二甲苯选择性下降，催化剂的表面酸性和孔结构对催化性能有很大影响。
The deactivation rate of catalyst can be reduced in supercritical reaction by SCFs' situ extraction of coke precursors. It is investigated in this dissertation that the alkylation of toluene with methanol for para-xylene over modified ZSM-5 zeolite on the conditions of reactants (mainly toluene) as supercritical reaction media.
The catalyst for alkylation is investigated at atmospheric pressure in order to find catalyst used in supercritical reaction. HZSM-5 is heated by steam and modified by Mg P and Si etc. It is found that conversion of toluene is 10% and selectivity of para-xylene is 68% on 800 hydrothermal catalyst without carrying gas when reaction temperature is 460. conversion of toluene is 7% and selectivity of para-xylene is 93% on Mg-modified catalyst.
In supercritical reaction, coke deposition can be reduced by supercritical fluid and life of catalyst is prolonged. On 800 hydrothermal catalyst, when reaction is carried out at 460 and atmospheric pressure, conversion of -toluene decreases after 20 hours of continue reaction. But at 460 , 5. 5MPa, conversion of toluene is maintained for 46 hours. Furthermore, on the catalyst selected conversion of toluene increases and selectivity of para-xylene decreases-but there is still selectivity, in supercritical reaction compared to reaction at air pressure.
It can be concluded that in supercritical reaction coke precursors can be extracted in situ and life of catalyst can be prolonged by supercritical fluids. Conversion of toluene increases while selectivity of para-xylene decreases in supercritical reaction. The catalysis character is greatly affected by acidity and pore structure of catalyst.
首先在常压下进行甲苯甲醇烷基化的研究，以找到用于超临界反应的催化剂。研究中对HZSM-5进行了水热、载镁、载磷、硅处理等改性处理。发现在没有载气的条件下，800℃水热处理的催化剂甲苯转化率为11％，对二甲苯选择性为66％。载Mg催化剂甲苯转化率为7％，对二甲苯选择性为93％。
在超临界条件下，超临界流体能够抑制催化剂积炭，延长催化剂寿命。对于800℃水热处理SZ催化剂，在460℃，常压反应条件下，甲苯转化率在20h后就会下降，而在460℃，5.5MPa条件下，甲苯转化率在46h内保持稳定。另外，对所选择的催化剂体系，与常压气相反应相比，超临界条件下的反应中，甲苯转化率提高，对二甲苯的选择性下降，但是也具有一定的选择性。从而认为：在超临界条件下的反应中，超临界流体能萃取积炭前体、抑制催化剂失活；甲苯转化率提高，但对二甲苯选择性下降，催化剂的表面酸性和孔结构对催化性能有很大影响。
The deactivation rate of catalyst can be reduced in supercritical reaction by SCFs' situ extraction of coke precursors. It is investigated in this dissertation that the alkylation of toluene with methanol for para-xylene over modified ZSM-5 zeolite on the conditions of reactants (mainly toluene) as supercritical reaction media.
The catalyst for alkylation is investigated at atmospheric pressure in order to find catalyst used in supercritical reaction. HZSM-5 is heated by steam and modified by Mg P and Si etc. It is found that conversion of toluene is 10% and selectivity of para-xylene is 68% on 800 hydrothermal catalyst without carrying gas when reaction temperature is 460. conversion of toluene is 7% and selectivity of para-xylene is 93% on Mg-modified catalyst.
In supercritical reaction, coke deposition can be reduced by supercritical fluid and life of catalyst is prolonged. On 800 hydrothermal catalyst, when reaction is carried out at 460 and atmospheric pressure, conversion of -toluene decreases after 20 hours of continue reaction. But at 460 , 5. 5MPa, conversion of toluene is maintained for 46 hours. Furthermore, on the catalyst selected conversion of toluene increases and selectivity of para-xylene decreases-but there is still selectivity, in supercritical reaction compared to reaction at air pressure.
It can be concluded that in supercritical reaction coke precursors can be extracted in situ and life of catalyst can be prolonged by supercritical fluids. Conversion of toluene increases while selectivity of para-xylene decreases in supercritical reaction. The catalysis character is greatly affected by acidity and pore structure of catalyst.
引文
1, Weizs P.B.,and Frilette V.J.,Intracrystalline and molecular-shape-selective catalysis by zeolite salts.J.phy.Chem.1960,64:382
2, Kokotailo G.T.,Lawton S.L.,and Olson D.H.Nature 1978 272:438
3, Weisz P.B.7th.Int.Congr.Catal.1980
4, Yashima T.,Sakaguchi Y.,and Namba S.Stud.Surf.Sci.Catal.1981 7:739
5, Reading W.W.,Chu C.,Young L.B.Selective alkylation of toluene with methanol to produce para-xylene.J.Catal.,198167:159-174
6, Fraenkel D.et al.Proc.8th.Int.Cong.Catal.1984 4:545
7, Yashima,T.,Ahmad,H.,Yamazaki,K.,et al.Alkylation on synthetic zeloites.I.Alkylation of tulene with methanol.J.catal.,1970,16,273
8, Wendlandt K.P.,et al.Proc.8th.Int.Cong.Catal.IV-507
9,Weisz P.B.Molecular shape selective catalysis.Pure & Appl.Chem. 1980,52(9) :2091-2103
10,赵淑萱 甲苯甲醇烷基化制对二甲苯技术经济分析,天然气化工,1984,9 (3) :53-61
11,曾昭槐,潘贵生.二甲苯在ZSM-5分子筛中吸附与扩散.物理化学学报 1989 5 (2) :145-150
12,Sotelo T.L,Uguina M.A.,and Valverde J.L.et al.Reactivation of toluene alkylation with methanol over magnesium-modified ZSM-5． Shape selectivity changes induced by coke formation Appl.Catal.A:Generral 1994 (114) :273-287
13,Chen N.Y.,Kaeding W.W.and Dwyer F.G.Para-directed aromatic reactions over shape-selective molecular sieve zeolite catalysts.J.Am.Chem.Soc.1979 101(22) :6783-6784
14,Fraenkel D.,Leoy M.Comparative study of shape-selective toluene alkylations over HZSM-5． J.Catal.1989,118(1) :10-21
15,Vinek H.,Rumplmay G.and Lercher J.A.Catalytic properties of postsynthesis phosphorus-modififed H-ZSM5 zeolites.J.Catal.1989 115(1) :291-300
16,Reading W.W.,and Butter S.A.Production of chemicals from methanol.I:Low
molecular weight olefins. J. Catal. 1980 61(1) :155-164
17、王文月，沈俭一，葛欣．甲苯甲醇苯环烷基化ZSM-5沸石催化剂的吸附量热研究．燃料化学学报1998，26(4)：303-306
18、Sayed, M. B. and Vedrine, The effect of modification with Boron on the catalytic activity and selectivity of HZSM-5. J.C., J. Catal., 1986, 101(1) :43-55
19、曾昭槐，苏毅．硼改性HZSM-5沸石对甲苯乙基化的择形催化作用．燃料化学学报1989，17(1)：9-15
20、李书纹，王祥生．甲苯甲醇合成高纯度对二甲苯的研究．天然气化工1991，16(6)： 3-5
21、李国英，赵进才．锑改性HZSM-5上甲苯的对位选择性甲基化．石油化工1987，16 (5)：275-280
22、周日新，安胜恩，刘余章．ZSM-5沸石选择性催化作用的研究．Ⅱ甲苯烷基化选择性生成对二甲苯．催化学报1983，4(4)：303-306
23、赵进才，李国英，丁余庆．锑改性对HZSM-5酸性的影响．催化学报1988，9(2)：152-156
24、陈前均，汪长春，周淑兰等．ZSM-5分子筛的酸间性质和其催化性能．催化学报 1990，11(2)：127-131
25、刘杨，严爱珍，须沁华．中孔分子筛上择形烷基化反应的研究．Ⅰ反应条件对甲苯甲醇择形烷基化反应的影响．催化学报 1990，11(4)：328-331
26、Kiricsi I., Shimizu S.,Kiyozumi Y. et al. Alkylation of toluene with methanol over zeolitedisc catalyst synthesized via solid-state reactions. Appl. Catal. A, 1997, 156(1): 335-345
27、Sotelo J. L., Uguina M.A. , Valverde J.L. et al Kinetics of toluene alkylation with methanol over Mg-modified ZSM-5. Ind. Eng. Chem. Res., 1993, 32(11): 2548-2554
28、李玉光，余向阳，邓向念．芳烃在 HZSM-5沸石中的扩散．中山大学学报，1997，36(2)：83-86
29、Ahmed K. A, Sohair M.A., Eman A.E., Catalytic Para-xylene maximization Ⅱ-alkylation of loluene with methanol on platinum loaded' H-ZSM-5 zeolite Catalysts prepared via different routes. Appl. Catal. A:General 1999, 179:107-115
30, Ducarme V.,Vedrine J.C.ZSM-5 and ZSM-11 zeolites:influence of morphological and chemical parameters on catalytic selectivity and deactivation.Appl.Catal.,1985,17:175-184
31,Mirth G.,Cejka J.,Nasterer E.et al.Transition state and diffusion controlled shape selectivity in the formation and reaction of xylenes. Stud.Surf.Sci.Catal.(Catalysts Deactivation),1994,83:287-294
32,Subramaniam B,etal.Reactions in supercritical fluids [J].Ind Eng Chem Process Des Dev,1986,25 (1) :1-12．
33,董新法,李再资,林维明.超临界化学反应研究的新进展[J].现代化工,1997,17(11) :10-13．
34, Philip E.Savage,Sudhama Gopalan,Tahmid I.Mizan,Christopher J.Martino,and Eric E.Brock.Reactions at Supercritical Conditions:Applications and Fundamentals[J].AIChE J.July 1995,41 (7) :1723-1778
35,Baiker A.Supercritical Fluids in Heterogeneous Catalysis[J].Chem.Rev.1999,99,453-473
36,Hussain A.,Solid catalyzed supercritical isoparaffin-olefin alkylation process[P],US:5304698 1994-04-19．
37,Fan L.,Nakamura I.,Ishida S.,Fujimoto K.L.,Supercritical-Phase Alkylation Reaction on Solid Acid Catalysts:Mechanistic Study and.Catalyst Development[J].Ind.Eng.Chem.Res.1997,36(5) :1458-1463．
38,Funamoto G.,Tamura S.,Segawa K.,Wan K.,Davis M.E.,Isobutane alkylation over solid catalysts under supercritical conditions[J].Res.Chem.Intermed.1998,24(4) :449-459．
39, Corma A.,Martinez Z.,Martinez C.,Isobutane/2-butene alkylation on ultrastable Y zeolites:influence of zeolite unit cell size[J].J.Catal.1994,146(1) :185-192．
40,Clark M.C.,Subramaniam B.,Extended Alkylate Production Activity during Fixed-Bed Supercritical 1-Butane/Isobutane Alkylation on Solid Acid Catalysts Using Carbon Dioxide as a Diluent [J].Ind.Eng.Chem.Res.1998,37(4) :1243-1250．
41,Carlos A.Querini,Isobutane/butene alkylation of solid acid catalysts J.Catal.Today 2000 62:135-143
42,Subramaniam B,Arunajatesan V,Lyon C.J.,Stud.Surf.Sci.catal.1999,
126(catalyst Deactivat ion, 1999): 63-77.
43、A.S. Chellappa, R.C. Miller, W. J. Thomson, Supercritical alkylation and butene dimerization over sulfated zirconia and iron-manganese promoted sulfated zirco(?)ia catalysts[J].Appl. Catal. A:general 2001,209:359-347
44、何奕工．超临界流体状态下的异构烷烃与烯烃烷基化反应[J]．催化学报，1999，20(4)：403-408
45、何奕工，贺玉峰．固体酸烷基化催化剂表面上焦炭前身物的结构和物化表征[J]．催化学报，2000，21(2)：175-178
46、朱晓蒙，高勇，朱中南，袁渭康．超临界条件下苯烃化反应研究[J]．化工学报．1993，44(4)：502-505．
47、朱晓蒙，高勇，丁平，朱中南等．超临界苯烷基化催化剂的失活研究[J]．华东理工大学学报．1994，20(4)：422-425
48、Yi-feng Shi, Yong Gao,Ying-chun Dai,Wei-kang Yuan, Kinetics for benzene+ethylene reaction in near-critical regions[J].Chem. Eng. Sci. 56(2001):1403-1410
2, Kokotailo G.T.,Lawton S.L.,and Olson D.H.Nature 1978 272:438
3, Weisz P.B.7th.Int.Congr.Catal.1980
4, Yashima T.,Sakaguchi Y.,and Namba S.Stud.Surf.Sci.Catal.1981 7:739
5, Reading W.W.,Chu C.,Young L.B.Selective alkylation of toluene with methanol to produce para-xylene.J.Catal.,198167:159-174
6, Fraenkel D.et al.Proc.8th.Int.Cong.Catal.1984 4:545
7, Yashima,T.,Ahmad,H.,Yamazaki,K.,et al.Alkylation on synthetic zeloites.I.Alkylation of tulene with methanol.J.catal.,1970,16,273
8, Wendlandt K.P.,et al.Proc.8th.Int.Cong.Catal.IV-507
9,Weisz P.B.Molecular shape selective catalysis.Pure & Appl.Chem. 1980,52(9) :2091-2103
10,赵淑萱 甲苯甲醇烷基化制对二甲苯技术经济分析,天然气化工,1984,9 (3) :53-61
11,曾昭槐,潘贵生.二甲苯在ZSM-5分子筛中吸附与扩散.物理化学学报 1989 5 (2) :145-150
12,Sotelo T.L,Uguina M.A.,and Valverde J.L.et al.Reactivation of toluene alkylation with methanol over magnesium-modified ZSM-5． Shape selectivity changes induced by coke formation Appl.Catal.A:Generral 1994 (114) :273-287
13,Chen N.Y.,Kaeding W.W.and Dwyer F.G.Para-directed aromatic reactions over shape-selective molecular sieve zeolite catalysts.J.Am.Chem.Soc.1979 101(22) :6783-6784
14,Fraenkel D.,Leoy M.Comparative study of shape-selective toluene alkylations over HZSM-5． J.Catal.1989,118(1) :10-21
15,Vinek H.,Rumplmay G.and Lercher J.A.Catalytic properties of postsynthesis phosphorus-modififed H-ZSM5 zeolites.J.Catal.1989 115(1) :291-300
16,Reading W.W.,and Butter S.A.Production of chemicals from methanol.I:Low
molecular weight olefins. J. Catal. 1980 61(1) :155-164
17、王文月，沈俭一，葛欣．甲苯甲醇苯环烷基化ZSM-5沸石催化剂的吸附量热研究．燃料化学学报1998，26(4)：303-306
18、Sayed, M. B. and Vedrine, The effect of modification with Boron on the catalytic activity and selectivity of HZSM-5. J.C., J. Catal., 1986, 101(1) :43-55
19、曾昭槐，苏毅．硼改性HZSM-5沸石对甲苯乙基化的择形催化作用．燃料化学学报1989，17(1)：9-15
20、李书纹，王祥生．甲苯甲醇合成高纯度对二甲苯的研究．天然气化工1991，16(6)： 3-5
21、李国英，赵进才．锑改性HZSM-5上甲苯的对位选择性甲基化．石油化工1987，16 (5)：275-280
22、周日新，安胜恩，刘余章．ZSM-5沸石选择性催化作用的研究．Ⅱ甲苯烷基化选择性生成对二甲苯．催化学报1983，4(4)：303-306
23、赵进才，李国英，丁余庆．锑改性对HZSM-5酸性的影响．催化学报1988，9(2)：152-156
24、陈前均，汪长春，周淑兰等．ZSM-5分子筛的酸间性质和其催化性能．催化学报 1990，11(2)：127-131
25、刘杨，严爱珍，须沁华．中孔分子筛上择形烷基化反应的研究．Ⅰ反应条件对甲苯甲醇择形烷基化反应的影响．催化学报 1990，11(4)：328-331
26、Kiricsi I., Shimizu S.,Kiyozumi Y. et al. Alkylation of toluene with methanol over zeolitedisc catalyst synthesized via solid-state reactions. Appl. Catal. A, 1997, 156(1): 335-345
27、Sotelo J. L., Uguina M.A. , Valverde J.L. et al Kinetics of toluene alkylation with methanol over Mg-modified ZSM-5. Ind. Eng. Chem. Res., 1993, 32(11): 2548-2554
28、李玉光，余向阳，邓向念．芳烃在 HZSM-5沸石中的扩散．中山大学学报，1997，36(2)：83-86
29、Ahmed K. A, Sohair M.A., Eman A.E., Catalytic Para-xylene maximization Ⅱ-alkylation of loluene with methanol on platinum loaded' H-ZSM-5 zeolite Catalysts prepared via different routes. Appl. Catal. A:General 1999, 179:107-115
30, Ducarme V.,Vedrine J.C.ZSM-5 and ZSM-11 zeolites:influence of morphological and chemical parameters on catalytic selectivity and deactivation.Appl.Catal.,1985,17:175-184
31,Mirth G.,Cejka J.,Nasterer E.et al.Transition state and diffusion controlled shape selectivity in the formation and reaction of xylenes. Stud.Surf.Sci.Catal.(Catalysts Deactivation),1994,83:287-294
32,Subramaniam B,etal.Reactions in supercritical fluids [J].Ind Eng Chem Process Des Dev,1986,25 (1) :1-12．
33,董新法,李再资,林维明.超临界化学反应研究的新进展[J].现代化工,1997,17(11) :10-13．
34, Philip E.Savage,Sudhama Gopalan,Tahmid I.Mizan,Christopher J.Martino,and Eric E.Brock.Reactions at Supercritical Conditions:Applications and Fundamentals[J].AIChE J.July 1995,41 (7) :1723-1778
35,Baiker A.Supercritical Fluids in Heterogeneous Catalysis[J].Chem.Rev.1999,99,453-473
36,Hussain A.,Solid catalyzed supercritical isoparaffin-olefin alkylation process[P],US:5304698 1994-04-19．
37,Fan L.,Nakamura I.,Ishida S.,Fujimoto K.L.,Supercritical-Phase Alkylation Reaction on Solid Acid Catalysts:Mechanistic Study and.Catalyst Development[J].Ind.Eng.Chem.Res.1997,36(5) :1458-1463．
38,Funamoto G.,Tamura S.,Segawa K.,Wan K.,Davis M.E.,Isobutane alkylation over solid catalysts under supercritical conditions[J].Res.Chem.Intermed.1998,24(4) :449-459．
39, Corma A.,Martinez Z.,Martinez C.,Isobutane/2-butene alkylation on ultrastable Y zeolites:influence of zeolite unit cell size[J].J.Catal.1994,146(1) :185-192．
40,Clark M.C.,Subramaniam B.,Extended Alkylate Production Activity during Fixed-Bed Supercritical 1-Butane/Isobutane Alkylation on Solid Acid Catalysts Using Carbon Dioxide as a Diluent [J].Ind.Eng.Chem.Res.1998,37(4) :1243-1250．
41,Carlos A.Querini,Isobutane/butene alkylation of solid acid catalysts J.Catal.Today 2000 62:135-143
42,Subramaniam B,Arunajatesan V,Lyon C.J.,Stud.Surf.Sci.catal.1999,
126(catalyst Deactivat ion, 1999): 63-77.
43、A.S. Chellappa, R.C. Miller, W. J. Thomson, Supercritical alkylation and butene dimerization over sulfated zirconia and iron-manganese promoted sulfated zirco(?)ia catalysts[J].Appl. Catal. A:general 2001,209:359-347
44、何奕工．超临界流体状态下的异构烷烃与烯烃烷基化反应[J]．催化学报，1999，20(4)：403-408
45、何奕工，贺玉峰．固体酸烷基化催化剂表面上焦炭前身物的结构和物化表征[J]．催化学报，2000，21(2)：175-178
46、朱晓蒙，高勇，朱中南，袁渭康．超临界条件下苯烃化反应研究[J]．化工学报．1993，44(4)：502-505．
47、朱晓蒙，高勇，丁平，朱中南等．超临界苯烷基化催化剂的失活研究[J]．华东理工大学学报．1994，20(4)：422-425
48、Yi-feng Shi, Yong Gao,Ying-chun Dai,Wei-kang Yuan, Kinetics for benzene+ethylene reaction in near-critical regions[J].Chem. Eng. Sci. 56(2001):1403-1410