催化剂Zn-Sr-SiO_2的制备及其对甲醇脱氢制备无水甲醛的催化性能
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摘要
采用溶胶凝胶法制备了催化剂Zn-Sr-SiO_2,其结构经SEM、 XRD、 N_2吸附/脱附、NH_3-TPD和CO_2-TPD表征。利用固定床反应器评价了Zn-Sr-SiO_2对甲醇脱氢制备无水甲醛反应的催化性能。研究了焙烧温度,Zn负载量,Zn/Sr摩尔比,载气流量,质量空速等因素对催化性能的影响,以及催化剂的寿命、失活与再生。结果表明:制备催化剂的最佳条件为焙烧温度700℃, Zn负载量为15%, Zn/Sr为5/1。反应温度为600℃,甲醇的质量空速为4.47 h~(-1)时,甲醇的转化率为25.35%,甲醛的选择性为91.98%。催化剂寿命为33 h。再生后,催化剂的中强碱性位得到了再生。
Zn-Sr-SiO_2 catalysts were prepared by sol-gel method. The structures were characterized by SEM, XRD, N_2 adsorption/desorption, NH_3-TPD and CO_2-TPD. Catalytic performances of Zn-Sr-SiO_(2 )catalysts for dehydrogenation of methanol to formaldehyde were tested in fixed-bed reactor. The effects of calcination temperature, Zn loading, n_(Zn)/n_(Sr), carrier gas flow and mass space velocity on the catalytic performances were investigated. The lifetime, deactivation and regeneration of the catalysts were investigated as well. The results showed that the optimum preparation conditions of catalyst were as follows: calcination temperature was 700 ℃, loading of Zn was 15%, ratio of n_(Zn)/n_(Sr) was 5/1. Under the reaction conditions of the reaction temperature of 600 ℃ and the mass space velocity of methanol of 4.47 h~(-1), the conversion of methanol and the selectivity of formaldehyde were 25.35% and 91.98%, respectively. The lifespan of the catalyst was 33 h and the medium strong alkaline sites of Zn-Sr-SiO_2 catalyst have been regenerated.
Zn-Sr-SiO_2 catalysts were prepared by sol-gel method. The structures were characterized by SEM, XRD, N_2 adsorption/desorption, NH_3-TPD and CO_2-TPD. Catalytic performances of Zn-Sr-SiO_(2 )catalysts for dehydrogenation of methanol to formaldehyde were tested in fixed-bed reactor. The effects of calcination temperature, Zn loading, n_(Zn)/n_(Sr), carrier gas flow and mass space velocity on the catalytic performances were investigated. The lifetime, deactivation and regeneration of the catalysts were investigated as well. The results showed that the optimum preparation conditions of catalyst were as follows: calcination temperature was 700 ℃, loading of Zn was 15%, ratio of n_(Zn)/n_(Sr) was 5/1. Under the reaction conditions of the reaction temperature of 600 ℃ and the mass space velocity of methanol of 4.47 h~(-1), the conversion of methanol and the selectivity of formaldehyde were 25.35% and 91.98%, respectively. The lifespan of the catalyst was 33 h and the medium strong alkaline sites of Zn-Sr-SiO_2 catalyst have been regenerated.
引文
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[3] 李峰.我国甲醛行业的发展动态[J].化学工业,2015,(05):23-26.
[4] 李晓云,孙彦民,于海斌.甲醇催化脱氢制无水甲醛研究进展[C].第七届全国工业催化技术及应用年会,2010.
[5] UHLRICH J J,YANG B,SHAIKHUTDINOVS.Methanol reactivity on silica-supported ceria nanoparticles[J].Topics in Catalysis,2014,57(14-16):1229-1235.
[6] PRICE S P,TONG X,RIDGE C,et al.Catalytic oxidation of methanol to formaldehyde by mass-selected vanadium oxide clusters supported on a TiO2(110) surface[J].Journal of Physical Chemistry A,2014,118(37):8309-8313.
[7] KROPP T,PAIER J,SAUER J.Support effect in oxide catalysis:Methanol oxidation onvanadia/ceria[J].Journal of the American Chemical Society,2014,136(41):14616-14625.
[8] RUF S,MAY A,EMIG G.Anhydrous formaldehyde by sodium catalysis[J].Applied Catalysis a-General,2001,213(2):203-215.
[9] LI H J,LAUSCHE A C,PETERSON A A,et al.Using microkinetic analysis to search for novel anhydrous formaldehyde production catalysts[J].Surface Science,2015,641:105-111.
[10] TU W,CHIN Y H.Catalytic consequences of the identity and coverages of reactive intermediates during methanol partial oxidation on Pt clusters[J].Journal of Catalysis,2014,313:55-69.
[11] SHAN J J,LUCCI F R,LIU J L,et al.Water co-catalyzed selective dehydrogenation of methanol to formaldehyde and hydrogen[J].Surface Science,2016,650:121-129.
[12] BOUCHER M B,MARCINKOWSKI M D,LIRIANO M L,et al.Molecular-scale perspective of water-catalyzed methanol dehydrogenation to formaldehyde[J].ACS Nano,2013,7(7):6181-6187.
[13] LAUSCHE A C,HUMMELSHOJ J S,ABILD-PEDERSEN F,et al.Application of a new informatics tool in heterogeneous catalysis:Analysis of methanol dehydrogenation on transition metal catalysts for the production of anhydrous formaldehyde[J].Journal of Catalysis,2012,291:133-137.
[14] REN L P,DAI W L,YANG X L,et al.Direct dehydrogenation of methanol to formaldehyde over pre-treated polycrystalline silver catalyst[J].Catalysis Letters,2005,99(1-2):83-87.
[15] MUSIC A,BATISTA J,LEVEC J.Gas-phase catalytic dehydrogenation of methanol to formaldehyde over ZnO/SiO2 based catalysts,zeolites,and phosphates[J].Applied Catalysis a-General,1997,165(1-2):115-131.
[16] SAGOU M.Formaldehyde Prodn by catalytic dehydrogenation of methanol-using zinc oxide and/or indium oxide with or without silica as catalyst:JP 60006629-A[P].1988.
[17] 任丽萍,戴维林,范康年,等.高活性Ag/SiO2-ZnO催化剂的制备及其催化甲醇脱氢制无水甲醛的研究[C].中国化工学会2005年石油化工学术年会,2005.
[18] YANG Z,LI J,YANG X G,et al.Gas-phase oxidation of alcohols over silver:The extension of catalytic cycles of oxidation of alcohols in liquid-phase[J].Journal of Molecular Catalysis a-Chemical,2005,241(1-2):15-22.
[19] 李勇斌.甲醇直接脱氢制无水甲醛含钠化合物催化性能的研究[D].太原:太原理工大学,2005.
[20] 张跃,崔志强,严生虎.Zn-ZrO2/SiO2非氧化脱氢制无水甲醛的研究[J]现代化工,2011,(02):64-67.
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