球磨时间对甲醇氧化制甲醛铁钼催化剂结构及性能的影响
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摘要
在无溶剂条件下,以可溶性铁盐和钼酸盐为原料,采用机械球磨法在不同球磨时间下制备铁钼催化剂,采用XRD、SEM、EDS技术对催化剂的晶体结构、形貌和组成进行表征,并利用微型固定床石英管反应器考察铁钼催化剂氧化甲醇制甲醛的性能。结果表明,当球磨时间在30~90 min时,XRD结果表明含有Fe_2(MoO_4)_3和MoO_3衍射峰,无明显杂晶峰,样品形貌主要由颗粒和少许片状结构组成;在反应温度为285℃、质量空速为1.27 h-1条件下,甲醇转化率均接近100%,甲醛选择性差别较小,约为95%。
Iron molybdenum catalyst is successfully synthesized via mechanochemistry method with soluble iron salt and molybdates as raw materials under solvent-free conditions at different time of ball milling.The structure,morphology and composition of prepared catalyst are investigated by using X-ray diffraction(XRD),scanning electron microscope(SEM) and energy dispersive X-ray detector(EDS).The catalytic performance of prepared catalyst is evaluated through the oxidation of methanol to make formaldehyde in a fixed bed quartz tube micro-reactor.The results via XRD show that the prepared catalyst samples are assigned to Fe_2(MoO_4)_3 and MoO_3,without obvious mixed phase peaks and present a large amount of fine grains and very few flake-like when the time of ball milling is in the range of 30-90 min.The conversion rate of methanol approaches to 100% and the selectivity of formaldehyde is about 95% when the prepared catalyst is served,the weight hourly space velocity is 1.27 h-1,and the reaction temperature is at 285℃.
Iron molybdenum catalyst is successfully synthesized via mechanochemistry method with soluble iron salt and molybdates as raw materials under solvent-free conditions at different time of ball milling.The structure,morphology and composition of prepared catalyst are investigated by using X-ray diffraction(XRD),scanning electron microscope(SEM) and energy dispersive X-ray detector(EDS).The catalytic performance of prepared catalyst is evaluated through the oxidation of methanol to make formaldehyde in a fixed bed quartz tube micro-reactor.The results via XRD show that the prepared catalyst samples are assigned to Fe_2(MoO_4)_3 and MoO_3,without obvious mixed phase peaks and present a large amount of fine grains and very few flake-like when the time of ball milling is in the range of 30-90 min.The conversion rate of methanol approaches to 100% and the selectivity of formaldehyde is about 95% when the prepared catalyst is served,the weight hourly space velocity is 1.27 h-1,and the reaction temperature is at 285℃.
引文
[1]Leo E Heim,Hannelore Konnerth,Martin H G Prechtl.Future perspectives for formaldehyde:Pathways for reductive synthesis and energy storage[J].Green Chemistry,2017,19:2347-2355.
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[3]Ana Paula Vieira Soares,Manuel Farinha Portela,Alain Kiennemann.Methanol selective oxidation to formaldehyde over iron-molybdate catalysts[J].Catalysis Reviews,2004,47:125-174.
[4]Matthew P House,Albert F Carley,Michael Bowker.Selective oxidation of methanol on iron molybdate catalysts and the effects of surface reduction[J].Journal of Catalysis,2007,252:88-96.
[5]Sum-Kou M R,Mendioroz S,Fierro J L G,et al.Influence of the preparation method on the behavior of Fe-Mo catalysts for the oxidation of methanol[J].Journal of Materials Science,1995,30(2):496-503.
[6]Matthew P House,Albert F Carley,Michael Bowker.Selective oxidation of methanol on iron molybdate catalysts and the effects of surface reduction[J].Journal of Catalysis,2007,252:88-96.
[7]Matthew P House,Albert F Carley,Ricardo Echeverria-Valda,et al.Effect of varying the cation ratio within iron molybdate catalysts for the selective oxidation of methanol[J].The Journal of Physical Chemistry C,2008,112:4333-4341.
[8]Huang Yan,Cong Liyan,Yu Jian,et al.The surface evolution of a catalyst jointly influenced by thermal spreading and solid-state reaction:A case study with an Fe2O3-Mo O3system[J].Journal of Molecular Catalysis A:Chemical,2009,302:48-53.
[9]Ana Paula,Vieira Soares,Manuel Farinha Portela,et al.Mechanism of deactivation of iron-molybdate catalysts prepared by coprecipitation and sol-gel techniques in methanol to formaldehyde oxidation[J].Chemical Engineering Science,2003,58:1315-1322.
[10]张帅,张一科,呼日勒朝克图,等.甲醇氧化制甲醛铁钼催化剂表面结构与活性[J].化工学报,2016,67(9):3678-3683.
[11]忻新泉,周益明,牛云垠.低热固相化学反应[M].北京:高等教育出版社,2010.
[2]Ali Mohammad Bahmanpour,Andrew Hoadley,Samir H Mushrif,et al.Hydrogenation of carbon monoxide into formaldehyde in liquid media[J].ACS Sustainable Chemistry Engineering,2016,4:3970-3977.
[3]Ana Paula Vieira Soares,Manuel Farinha Portela,Alain Kiennemann.Methanol selective oxidation to formaldehyde over iron-molybdate catalysts[J].Catalysis Reviews,2004,47:125-174.
[4]Matthew P House,Albert F Carley,Michael Bowker.Selective oxidation of methanol on iron molybdate catalysts and the effects of surface reduction[J].Journal of Catalysis,2007,252:88-96.
[5]Sum-Kou M R,Mendioroz S,Fierro J L G,et al.Influence of the preparation method on the behavior of Fe-Mo catalysts for the oxidation of methanol[J].Journal of Materials Science,1995,30(2):496-503.
[6]Matthew P House,Albert F Carley,Michael Bowker.Selective oxidation of methanol on iron molybdate catalysts and the effects of surface reduction[J].Journal of Catalysis,2007,252:88-96.
[7]Matthew P House,Albert F Carley,Ricardo Echeverria-Valda,et al.Effect of varying the cation ratio within iron molybdate catalysts for the selective oxidation of methanol[J].The Journal of Physical Chemistry C,2008,112:4333-4341.
[8]Huang Yan,Cong Liyan,Yu Jian,et al.The surface evolution of a catalyst jointly influenced by thermal spreading and solid-state reaction:A case study with an Fe2O3-Mo O3system[J].Journal of Molecular Catalysis A:Chemical,2009,302:48-53.
[9]Ana Paula,Vieira Soares,Manuel Farinha Portela,et al.Mechanism of deactivation of iron-molybdate catalysts prepared by coprecipitation and sol-gel techniques in methanol to formaldehyde oxidation[J].Chemical Engineering Science,2003,58:1315-1322.
[10]张帅,张一科,呼日勒朝克图,等.甲醇氧化制甲醛铁钼催化剂表面结构与活性[J].化工学报,2016,67(9):3678-3683.
[11]忻新泉,周益明,牛云垠.低热固相化学反应[M].北京:高等教育出版社,2010.
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