Al-ITQ-13分子筛的酸处理及其在苯-甲醇烷基化中的应用
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摘要
以硅溶胶、九水硝酸铝、氧化锗为原料直接合成了Al-ITQ-13分子筛原粉,并利用0. 01 mol/L的盐酸对分子筛原粉进行脱锗处理。利用XRD、SEM、N2吸附-脱附、NH3-TPD、ICP-OES和IR等方法对酸处理前后的分子筛进行表征,并将其应用于苯-甲醇烷基化反应中,考察其催化性能。结果表明,在酸处理温度为120℃时,分子筛的骨架不受影响,比表面积和孔体积最大,脱锗率为22. 72%,苯的转化率为59. 3%,比处理前提高了7. 1%。
Al-ITQ-13 molecular sieve raw powder is directly synthesized from silica gel,aluminum nitrate nonahydrate and germanium oxide,then treated with 0. 01 mol·L-1 hydrochloric acid. The samples are characterized by means of XRD,SEM,N2 adsorption-desorption,NH3-TPD,ICP-OES and IR,and their catalytic performances are evaluated in the alkylation of benzene with methanol. It is verified that the backbone of molecular sieve will not be affected,and the specific surface area and pore volume of the treated molecular sieve will reach the largest when the molecular sieve raw powder is treated by hydrochloric acid at 120℃. By using the treated molecular sieve,the removal rate of germanium can reach about 22. 72% and the conversation of benzene can reach 59. 3% which is 7. 1 percentage points higher than that by using untreated samples.
Al-ITQ-13 molecular sieve raw powder is directly synthesized from silica gel,aluminum nitrate nonahydrate and germanium oxide,then treated with 0. 01 mol·L-1 hydrochloric acid. The samples are characterized by means of XRD,SEM,N2 adsorption-desorption,NH3-TPD,ICP-OES and IR,and their catalytic performances are evaluated in the alkylation of benzene with methanol. It is verified that the backbone of molecular sieve will not be affected,and the specific surface area and pore volume of the treated molecular sieve will reach the largest when the molecular sieve raw powder is treated by hydrochloric acid at 120℃. By using the treated molecular sieve,the removal rate of germanium can reach about 22. 72% and the conversation of benzene can reach 59. 3% which is 7. 1 percentage points higher than that by using untreated samples.
引文
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[14]Man A J M D,Santen R A V. The relation between zeolite framework structure and vibrational spectra[J]. Zeolites,1992,12(3):269-279.
[15]徐亚荣,董志新,徐新良,等.苯与甲醇烷基化反应动力学[J].化学反应工程与工艺,2014,30(2):188-192.
[16]Warren W,Kaeding. Conversion of methanol to hydrocarbons:Ⅲ.Methylation,ethylation and propylation of benzene with methanol[J].Journal of Catalysis,1988,114(2):271-276.
[17]Yan Zhao,Wei Tan,Hongyu Wu,et al.Effect of Pt on stability of nano-scale ZSM-5 catalyst for toluene alkylation with methanol into p-xylene[J].Catalysis Today,2011,160(1):179-183.
[2]Casta1eda R,Corma A,Fornés V,et al.Direct synthesis of a 9×10member ring zeolite(Al-ITQ-13):A highly shape-selective catalyst for catalytic cracking[J]. Journal of Catalysis,2006,238(1):79-87.
[3]Llopis F J,Sastre G,Corma A.Isomerization and disproportionation of m-xylene in a zeolite with 9-and 10-membered ding pores:Molecular dynamics and catalytic studies[J]. Journal of Catalysis,2006,242(1):195-206.
[4]Skistad W,Teketel S,Bleken F L,et al.Methanol conversion to hydrocarbons(MTH)over H-ITQ-13(ITH)zeolite[J]. Topics in Catalysis,2014,57(1-4):143-158.
[5]Zeng P H,Liang Y,Ji S F,et al.Preparation of phosphorus-modified PITQ-13 catalysts and their performance in 1-butene catalytic cracking[J].J Energy Chem,2014,23:193-200.
[6]Zeng P H,Ji S F,Liang Y,et al.Alkali modification of Al-ITQ-13zeolite and its performances for catalytic cracking[J]. Petrochem Technol,2014,43(4):405-411.
[7]Xu R,Pang W,Yu J,et al. Chemistry of Zeolites and Related Porous Materials:Synthesis and Structure[M]. New Jersey:John Wiley&Sons,2009.
[8]Vidal-Moya J A,Blasco T,Rey F,et al.Distribution of fluorine and germanium in a new zeolite structure ITQ-13 studied by 19 F nuclear magnetic resonance[J]. Cheminform,2003,15(21):3961-3963.
[9]Liu X,Chu Y,Qiang W,et al. Identification of double four-ring units in germanosilicate ITQ-13 zeolite by solid-state NMR spectroscopy[J].Solid State Nucl Magn Reson,2017,87:1-9.
[10]Wu P,Ruan J,Wang L,et al. Methodology for synthesizing crystalline metallosilicates with expanded pore windows through molecular alkoxysilylation of zeolitic lamellar precursors[J].Journal of the American Chemical Society,2008,130(26):8178-8187.
[11]Liu X,Kasian N,Tuel A. New insights into the degermanation process of ITQ-17 zeolites[J]. Microporous&Mesoporous Materials,2014,190:171-180.
[12]徐浩,蒋金刚,杨博婷,等.同晶取代法稳固硅锗分子筛结构的研究[C]//全国分子筛学术大会会议.2013.
[13]Blasco T,Corma A,Ma J D,et al.Preferential location of Ge in the double four-membered ring units of ITQ-7 zeolite[J]. Journal of Physical Chemistry B,2002,106(10):2634-2642.
[14]Man A J M D,Santen R A V. The relation between zeolite framework structure and vibrational spectra[J]. Zeolites,1992,12(3):269-279.
[15]徐亚荣,董志新,徐新良,等.苯与甲醇烷基化反应动力学[J].化学反应工程与工艺,2014,30(2):188-192.
[16]Warren W,Kaeding. Conversion of methanol to hydrocarbons:Ⅲ.Methylation,ethylation and propylation of benzene with methanol[J].Journal of Catalysis,1988,114(2):271-276.
[17]Yan Zhao,Wei Tan,Hongyu Wu,et al.Effect of Pt on stability of nano-scale ZSM-5 catalyst for toluene alkylation with methanol into p-xylene[J].Catalysis Today,2011,160(1):179-183.