摘要
本文报导了w-Mn体系催化剂的甲烷氧化偶联反应性能,详细考察了反应条件对1.9wt％Mn—5wt％Na_2WO_4/SiO_2(W—34)催化剂反应性能的影响,并用XRD、BET、EPR、UV-DRS等方法对该催化剂进行了表征。结果表明,该催化剂具有较好的甲烷氧化偶联反应性能,在T=800C,甲烷空速=36,000ml·g^(-1)·h^(-1),CH_4:O_2:N_2=3:1:2.6的最佳实验条件下,其甲烷转化率为36.8％,C_2烃收率达到23.9％;研究还表明,C_2H_6,CO_2是CH_1氧化的一次产物,C_2H_4主要由C_2H_6脱氢而来,而CO则可能主要来源于C_2烃的表面深度氧化,催化剂的结构研究表明,在该催化剂中,w是以Na_2WO_4形式存在,Mn则以Mn_2O_3形式存在,而SiO_2已由无定型结构转变成u-方石英;W、Mn、Si之间没有形成新的化合物。
A series of W-Mn compounds were studied as catalysts for the oxidative coupling of methane (OCM) in a mixture of CH4/O2 and N2 gases by a fixed-bed flow reactor. The effects of reaction conditions on the reactivity of 1. 9 wt% Mn - 5wt% Na2WO4/SiO2(W-34) catalyst were investigated extensively.W-34 catalyst was prepared by two different procedures - impregnating and physically mixing method. The catalyst was dried at 110℃and then calcined in air at 750-850℃ for 4- 8 h.The results show that W-34 catalyst has good reactivity of OCM. A maximum in C2-yield of 23. 9% was obtained at T=800℃, GHSV of CH4 = 36000 ml ?g-1 ?h-1, CH4:O2 : N2 = 3: 1: 2. 6 and 101 kPa. The effects of operating conditions on W-34 catalyst performance helped elucidate the possible reaction paths for the various products.Structural characterization demonstrated that SiO2 was transformed from amorphous intoα-cristobalite structure. The tungsten- oxygen- silicon species originated from the interaction between Na2WO4 and SiO2 may be the active site for methane activation. There was no new phase formed in the catalyst, except the Na2WO4 and Mn2O3 phase.
出处
《分子催化》
EI
CAS
CSCD
1992年第6期427-433,共7页
Journal of Molecular Catalysis(China)
关键词
催化剂
甲烷
氧化
偶联
乙烯
Mn2O3
Na2WO4
Catalyst
Oxidative couping of methane.
