多级孔道ZSM-22分子筛的合成及其正庚烷加氢异构反应性能
|
摘要
为了将正庚烷变成辛烷值较高的单支链或多支链异构烷烃来提高汽油组分的辛烷值和燃烧效率,采用球磨-重结晶的方法制备了多级孔道ZSM-22-M-R-2分子筛和常规水热法合成了ZSM-22-C分子筛,进而通过浸渍法制备了含Pt量为0.5%的催化剂。借助X射线粉末衍射、扫描电镜、N2物理吸附、氨吸附-程序升温脱附、吡啶红外光谱表征手段分析了催化剂样品的结构和酸性。在固定床反应器中,研究了这两种催化剂的正庚烷加氢异构反应性能。结果表明:ZSM-22-M-R-2分子筛具有的酸量和ZSM-22-C分子筛相当,但具有更小的粒径;其异构化反应活性、异构产物的选择性和收率均高于常规ZSM-22-C分子筛。在反应温度为300℃时,异构产物的最大收率为68%。
In order to increase n-heptane into a single-chain or multi-branched isoparaffin with a higher octane number to improve the octane number and combustion efficiency of the gasoline component The ZSM-22-M-R-2 zeolite and ZSM-22-C zeolite have been synthesized using ball milling-recrystallization method and conventional hydrothermal method respectively. Then Pt-loaded catalysts were prepared by impregnation treatment for comparison of catalytic performance in hydroisomerization of n-Heptane which was hypothesized for production of isomers with high octane number. As-synthesized samples were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), nitrogen adsorption, ammonia temperature-programmed desorption(NH3-TPD) and pyridine adsorption infrared spectroscopy(Py-IR) for the elucidation of relationship between catalytic properties and structural characteristic and acidity. Research was conducted over bench-scale fixed-bed reactor and results showed that Pt/ZSM-22-M-R-2 with smaller crystal size has higher reactivity and selectivity in hydroisomerization of n-Heptane compared with Pt/ZSM-22-C, meanwhile they have similar acid amount. The highest attainable isomerization yield of 68% was obtained when reaction temperature was set to 300 ℃.
In order to increase n-heptane into a single-chain or multi-branched isoparaffin with a higher octane number to improve the octane number and combustion efficiency of the gasoline component The ZSM-22-M-R-2 zeolite and ZSM-22-C zeolite have been synthesized using ball milling-recrystallization method and conventional hydrothermal method respectively. Then Pt-loaded catalysts were prepared by impregnation treatment for comparison of catalytic performance in hydroisomerization of n-Heptane which was hypothesized for production of isomers with high octane number. As-synthesized samples were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), nitrogen adsorption, ammonia temperature-programmed desorption(NH3-TPD) and pyridine adsorption infrared spectroscopy(Py-IR) for the elucidation of relationship between catalytic properties and structural characteristic and acidity. Research was conducted over bench-scale fixed-bed reactor and results showed that Pt/ZSM-22-M-R-2 with smaller crystal size has higher reactivity and selectivity in hydroisomerization of n-Heptane compared with Pt/ZSM-22-C, meanwhile they have similar acid amount. The highest attainable isomerization yield of 68% was obtained when reaction temperature was set to 300 ℃.
引文
[1]Li Y,Sun H,Wang Y,et al.Green routes for synthesis of zeolites[J].Chemical reviews,2013,114(2):1521-1543.
[2]Seo Y,Lee S,Jo C,et al.Microporous aluminophosphate nanosheets and their nanomorphic zeolite analogues tailored by hierarchical structure-directing amines[J].Journal of the American Chemical Society,2013,135(24):8806-8809.
[3]Cundy C S,Cox P A.The hydrothermal synthesis of zeolites:history and development from the earliest days to the present time[J].Chemical Reviews,2003,103(3):663-702.
[4]Davis M E.Ordered porous materials for emerging applications[J].Nature,2002,417(6891):813-821.
[5]Boronat M,Corma A.Factors controlling the acidity of zeolites[J].Catalysis Letters,2015,145(1):162-172.
[6]Weisz P B,Swegler E W.Stepwise reaction on separate catalytic centers:isomerization of saturated hydrocarbons[J].Science,1957,126(3262):31-32.
[7]Mériaudeau P,Tuan V A,Lefebvre F,et al.Isomorphous substitution of silicon in the Al PO4 framework with AEL structure:n-octane hydroconversion[J].Microporous&Mesoporous Materials,1998,22(1-3):435-449.
[8]Claude M C,Vanbutsele G,Martens J A.Dimethyl branching of long n-alkanes in the range from decane to tetracosane on Pt/H-ZSM-22bifunctional catalyst[J].Journal of Catalysis,2001,203(1):213-231.
[9]Martens J A,Souverijns W,Verrelst W,et al.Selective isomerization of hydrocarbon chains on external surfaces of zeolite crystals[J].Angewandte Chemie International Edition,1995,34(22):2528-2530.
[10]Raybaud P,Patrigeon A,Toulhoat H.The origin of the C7-hydroconversion selectivities on Y,β,ZSM-22,ZSM-23,and EU-1zeolites[J].Journal of Catalysis,2001,197(1):98-112.
[11]Maesen T L M,Schenk M,Vlugt T J H,et al.The shape selectivity of paraffin hydroconversion on TON-,MTT-,and AEL-Type sieves[J].Journal of Catalysis,1999,188(2):403-412.
[12]Mériaudeau P,Tuan V A,Nghiem V T,et al.SAPO-11,SAPO-31,and SAPO-41 molecular sieves:synthesis,characterization,and catalytic properties in n-octane hydroisomerization[J].Journal of Catalysis,1997,169(1):55-66.
[13]Zhang S,Chen S L,Dong P,et al.Characterization and hydroisomerization performance of SAPO-11 molecular sieves synthesized in different media[J].Applied Catalysis A:General,2007,332(1):46-55.
[14]Kikhtyanin O V,Toktarev A V,Reznichenko I D,et al.Hydroisomerization of diesel fractions on platinum-containing silicoaluminophosphate SAPO-31:from the laboratory to the pilot scale[J].Petroleum Chemistry,2009,49(1):74-78.
[15]Wu W,Zhang Y,Wang W,et al.Hydroisomerization of n-hexadecane over the Pd-Ni2P/SAPO-31 bifunctional catalyst:synergistic effects of bimetallic active sites[J].Catalysis Science&Technology,2018,8(3):817-828.
[16]Mériaudeau P,Tuan V A,Nghiem V T,et al.Comparative evaluation of the catalytic properties of SAPO-31 and ZSM-48 for the hydroisomerization of n-Octane:effect of the acidity[J].Journal of Catalysis,1999,185(2):435-444.
[17]Martens J A,Verboekend D,Thomas K,et al.Hydroisomerization and hydrocracking of linear and multibranched long model alkanes on hierarchical Pt/ZSM-22 zeolite[J].Catalysis Today,2013,218:135-142.
[18]Wang G,Liu Q,Su W,et al.Hydroisomerization activity and selectivity of n-dodecane over modified Pt/ZSM-22 catalysts[J].Applied Catalysis A:General,2008,335(1):20-27.
[19]Choudhury I R,Hayasaka K,Thybaut J W,et al.Pt/H-ZSM-22 hydroisomerization catalysts optimization guided by single-event microkinetic modeling[J].Journal of Catalysis,2012,290(12):165-176.
[20]Lee S W,Ihm S K.Hydroisomerization and hydrocracking over platinum loaded ZSM-23 catalysts in the presence of sulfur and nitrogen compounds for the dewaxing of diesel fuel[J].Fuel,2014,134(9):237-243.
[21]Lee S W,Ihm S K.Characteristics of magnesium-promoted Pt/ZSM-23 catalyst for the hydroisomerization of n-hexadecane[J].Industrial&Engineering Chemistry Research,2013,52(44):15359-15365.
[22]Zhang M,Chen Y,Wang L,et al.Shape selectivity in hydroisomerization of hexadecane over Pt supported on 10-Ring zeolites:ZSM-22,ZSM-23,ZSM-35,and ZSM-48[J].Industrial&Engineering Chemistry Research,2016,55(21):6069-6078.
[23]Muraza O.Maximizing diesel production through oligomerization:a landmark opportunity for zeolite research[J].Industrial&Engineering Chemistry Research,2015,54(3):781-789.
[24]Jin D,Liu Z,Zheng J,et al.Nonclassical from-shell-to-core growth of hierarchically organized SAPO-11 with enhanced catalytic performance in hydroisomerization of n-heptane[J].RSC Advances,2016,6(39):32523-32533.
[25]Wu X,Qiu M,Chen X,et al.Enhanced n-dodecane hydroisomerization performance by tailoring acid sites on bifunctional Pt/ZSM-22via alkaline treatment[J].New Journal of Chemistry,2018,42(1):111-117.
[26]Li Y,Liu L,Zou X,et al.Nanocrystalline TON-type zeolites synthesized under static conditions[J].Microporous&Mesoporous Materials,2018,256:84-90.
[27]Wakihara T,Sato K,Inagaki S,et al.Fabrication of fine zeolite with improved catalytic properties by bead milling and alkali treatment[J].ACS Applied Materials&Interfaces,2010,2(10):2715-2718.
[28]Yang M,Tian P,Wang C,et al.A top-down approach to prepare silicoaluminophosphate molecular sieve nanocrystals with improved catalytic activity[J].Chemical Communications,2014,50(15):1845-1847.
[29]Wakihara T,Sato K,Sato K,et al.Preparation of nano-zeolite X by bead-milling and post-milling recrystallization[J].Journal of the Ceramic Society of Japan,2012,120(1404):341-343.
[30]Liu S,Ren J,Zhu S,et al.Synthesis and characterization of the Fe-substituted ZSM-22 zeolite catalyst with high n-dodecane isomerization performance[J].Journal of Catalysis,2015,330:485-496.
[2]Seo Y,Lee S,Jo C,et al.Microporous aluminophosphate nanosheets and their nanomorphic zeolite analogues tailored by hierarchical structure-directing amines[J].Journal of the American Chemical Society,2013,135(24):8806-8809.
[3]Cundy C S,Cox P A.The hydrothermal synthesis of zeolites:history and development from the earliest days to the present time[J].Chemical Reviews,2003,103(3):663-702.
[4]Davis M E.Ordered porous materials for emerging applications[J].Nature,2002,417(6891):813-821.
[5]Boronat M,Corma A.Factors controlling the acidity of zeolites[J].Catalysis Letters,2015,145(1):162-172.
[6]Weisz P B,Swegler E W.Stepwise reaction on separate catalytic centers:isomerization of saturated hydrocarbons[J].Science,1957,126(3262):31-32.
[7]Mériaudeau P,Tuan V A,Lefebvre F,et al.Isomorphous substitution of silicon in the Al PO4 framework with AEL structure:n-octane hydroconversion[J].Microporous&Mesoporous Materials,1998,22(1-3):435-449.
[8]Claude M C,Vanbutsele G,Martens J A.Dimethyl branching of long n-alkanes in the range from decane to tetracosane on Pt/H-ZSM-22bifunctional catalyst[J].Journal of Catalysis,2001,203(1):213-231.
[9]Martens J A,Souverijns W,Verrelst W,et al.Selective isomerization of hydrocarbon chains on external surfaces of zeolite crystals[J].Angewandte Chemie International Edition,1995,34(22):2528-2530.
[10]Raybaud P,Patrigeon A,Toulhoat H.The origin of the C7-hydroconversion selectivities on Y,β,ZSM-22,ZSM-23,and EU-1zeolites[J].Journal of Catalysis,2001,197(1):98-112.
[11]Maesen T L M,Schenk M,Vlugt T J H,et al.The shape selectivity of paraffin hydroconversion on TON-,MTT-,and AEL-Type sieves[J].Journal of Catalysis,1999,188(2):403-412.
[12]Mériaudeau P,Tuan V A,Nghiem V T,et al.SAPO-11,SAPO-31,and SAPO-41 molecular sieves:synthesis,characterization,and catalytic properties in n-octane hydroisomerization[J].Journal of Catalysis,1997,169(1):55-66.
[13]Zhang S,Chen S L,Dong P,et al.Characterization and hydroisomerization performance of SAPO-11 molecular sieves synthesized in different media[J].Applied Catalysis A:General,2007,332(1):46-55.
[14]Kikhtyanin O V,Toktarev A V,Reznichenko I D,et al.Hydroisomerization of diesel fractions on platinum-containing silicoaluminophosphate SAPO-31:from the laboratory to the pilot scale[J].Petroleum Chemistry,2009,49(1):74-78.
[15]Wu W,Zhang Y,Wang W,et al.Hydroisomerization of n-hexadecane over the Pd-Ni2P/SAPO-31 bifunctional catalyst:synergistic effects of bimetallic active sites[J].Catalysis Science&Technology,2018,8(3):817-828.
[16]Mériaudeau P,Tuan V A,Nghiem V T,et al.Comparative evaluation of the catalytic properties of SAPO-31 and ZSM-48 for the hydroisomerization of n-Octane:effect of the acidity[J].Journal of Catalysis,1999,185(2):435-444.
[17]Martens J A,Verboekend D,Thomas K,et al.Hydroisomerization and hydrocracking of linear and multibranched long model alkanes on hierarchical Pt/ZSM-22 zeolite[J].Catalysis Today,2013,218:135-142.
[18]Wang G,Liu Q,Su W,et al.Hydroisomerization activity and selectivity of n-dodecane over modified Pt/ZSM-22 catalysts[J].Applied Catalysis A:General,2008,335(1):20-27.
[19]Choudhury I R,Hayasaka K,Thybaut J W,et al.Pt/H-ZSM-22 hydroisomerization catalysts optimization guided by single-event microkinetic modeling[J].Journal of Catalysis,2012,290(12):165-176.
[20]Lee S W,Ihm S K.Hydroisomerization and hydrocracking over platinum loaded ZSM-23 catalysts in the presence of sulfur and nitrogen compounds for the dewaxing of diesel fuel[J].Fuel,2014,134(9):237-243.
[21]Lee S W,Ihm S K.Characteristics of magnesium-promoted Pt/ZSM-23 catalyst for the hydroisomerization of n-hexadecane[J].Industrial&Engineering Chemistry Research,2013,52(44):15359-15365.
[22]Zhang M,Chen Y,Wang L,et al.Shape selectivity in hydroisomerization of hexadecane over Pt supported on 10-Ring zeolites:ZSM-22,ZSM-23,ZSM-35,and ZSM-48[J].Industrial&Engineering Chemistry Research,2016,55(21):6069-6078.
[23]Muraza O.Maximizing diesel production through oligomerization:a landmark opportunity for zeolite research[J].Industrial&Engineering Chemistry Research,2015,54(3):781-789.
[24]Jin D,Liu Z,Zheng J,et al.Nonclassical from-shell-to-core growth of hierarchically organized SAPO-11 with enhanced catalytic performance in hydroisomerization of n-heptane[J].RSC Advances,2016,6(39):32523-32533.
[25]Wu X,Qiu M,Chen X,et al.Enhanced n-dodecane hydroisomerization performance by tailoring acid sites on bifunctional Pt/ZSM-22via alkaline treatment[J].New Journal of Chemistry,2018,42(1):111-117.
[26]Li Y,Liu L,Zou X,et al.Nanocrystalline TON-type zeolites synthesized under static conditions[J].Microporous&Mesoporous Materials,2018,256:84-90.
[27]Wakihara T,Sato K,Inagaki S,et al.Fabrication of fine zeolite with improved catalytic properties by bead milling and alkali treatment[J].ACS Applied Materials&Interfaces,2010,2(10):2715-2718.
[28]Yang M,Tian P,Wang C,et al.A top-down approach to prepare silicoaluminophosphate molecular sieve nanocrystals with improved catalytic activity[J].Chemical Communications,2014,50(15):1845-1847.
[29]Wakihara T,Sato K,Sato K,et al.Preparation of nano-zeolite X by bead-milling and post-milling recrystallization[J].Journal of the Ceramic Society of Japan,2012,120(1404):341-343.
[30]Liu S,Ren J,Zhu S,et al.Synthesis and characterization of the Fe-substituted ZSM-22 zeolite catalyst with high n-dodecane isomerization performance[J].Journal of Catalysis,2015,330:485-496.