Kinetics of the partial oxidation of methanol over a Fe-Mo catalyst

被引:52
作者
Deshmukh, SARK [1 ]
Annaland, AVS [1 ]
Kuipers, JAM [1 ]
机构
[1] Univ Twente, Fac Sci & Technol, NL-7500 AE Enschede, Netherlands
关键词
catalytic oxidation; methanol; formaldehyde; carbon monoxide; kinetics; differential reactor;
D O I
10.1016/j.apcata.2005.05.005
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The intrinsic steady-state kinetics of the partial oxidation of methanol to formaldehyde over a commercial Fe-Mo catalyst has been studied experimentally in a differentially operated reactor at temperatures of 230-260 degrees C, over a wide range of methanol and oxygen concentrations. The principal products found were formaldehyde, water, dimethyl ether (DME) and dimethoxymethane (DMM). The kinetics of the formaldehyde formation from methanol could be well described with Langmuir-Hinshelwood kinetics, assuming two different metal oxide sites, one containing adsorbed oxygenates and the other one containing lattice oxygen. The presence of water vapor lowered the formaldehyde formation rate significantly, especially at lower water partial pressures. These results could be well explained in terms of competitive adsorption of water with methanol on the free active catalyst sites. For the most important side reactions, i.e. dimethyl ether formation as well as dimethoxymethane formation the forward reaction rates were determined from the selectivity data. The conversion rate of dimethyl ether to formaldehyde was also measured with separate experiments in the differential reactor. Carbon monoxide was not formed during the differential kinetic measurements of formaldehyde formation from methanol. Therefore, the rate of formaldehyde oxidation to CO was studied separately in a dual bed catalyst, where formaldehyde was formed in the first integral reactor at low temperatures and subsequently converted to CO in a differential reactor. The rate of CO formation was first order in formaldehyde and the oxygen dependency was the same as that for the formaldehyde formation from methanol. Rate expressions for all reactions were formulated based on the above assumptions and a multivariate Levenberg-Marquardt method was used to fit all the model constants to all the experiments for all reaction rates simultaneously, while additionally accounting for axial concentration profiles in the reactor. The observed influences of composition and temperature on the reaction rates could be well described. (c) 2005 Elsevier B.V. All rights reserved.
引用
收藏
页码:240 / 255
页数:16
相关论文
共 21 条
[1]   OXIDATIVE DEHYDROGENATION OF METHANOL TO FORMALDEHYDE [J].
ALLISON, JN ;
GODDARD, WA III .
JOURNAL OF CATALYSIS, 1985, 92 (01) :127-135
[2]  
BIPIN VN, 1968, KINET CATAL, V9, P510
[3]  
DENTE M, 1964, CHIM IND-MILAN, V46, P1326
[4]  
DESHMUKH SAR, 2005, IN PRESS IND ENG CHE
[5]   Methanol oxidative dehydrogenation in a catalytic packed-bed membrane reactor: experiments and model [J].
Diakov, V ;
Blackwell, B ;
Varma, A .
CHEMICAL ENGINEERING SCIENCE, 2002, 57 (09) :1563-1569
[6]   METHANOL PARTIAL OXIDATION AT LOW-TEMPERATURE [J].
EDWARDS, J ;
NICOLAIDIS, J ;
CUTLIP, MB ;
BENNETT, CO .
JOURNAL OF CATALYSIS, 1977, 50 (01) :24-34
[7]  
EVMENENKO NP, 1969, KINET CATAL, V10, P1071
[8]   STOICHIOMETRY AND STRUCTURAL EFFECTS IN ALCOHOL CHEMISORPTION-TEMPERATURE-PROGRAMMED DESORPTION ON MOO3 [J].
FARNETH, WE ;
STALEY, RH ;
SLEIGHT, AW .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1986, 108 (09) :2327-2332
[9]  
Gerberich H. R., 1994, FORMALDEHYDE ENCY CH, V11, P929
[10]   THEORETICAL CHEMISTRY COMES ALIVE - FULL PARTNER WITH EXPERIMENT [J].
GODDARD, WA .
SCIENCE, 1985, 227 (4689) :917-923