Desoxigenação de metanol com monoxido de carbono catalisada por compostos de metais de transição

AUTOR(ES)

Rochel Montero Lago

DATA DE PUBLICAÇÃO

1991

RESUMO

The catalytic effect of transition metal compounds in the presence of base has been studied for the deoxygenation of methanol with carbon monoxide. The compounds Mo(CO)6, Ni(acac)2, Mn(acac)2, Fe(CO)5, RhCl3.3H2O, Rh2Cl2(CO)4, RuCl3 and CO2 (CO)8 were used as catalyst precursors. Gas chromatographic analysis of the gas and liquid reaction products show hydrogen, methane, carbon monoxide, carbon dioxide, the alcohols ethanol, n-propanol, n-butanol and the esters methyl formate and methyl acetate. In the reactions carried out at 200°C methane formation is not observed even in the presence of catalyst. At 280°C, methane production is catalyzed by some of the transition metal compounds. Mo(CO)6 has no catalytic activity and Ni (acac)2 and Mn(acac)2 inhibit the methane formation at the beginning of the reactions. Co2 (CO)8 shows the highest catalytic activity for methane production, which also depends on the base concentration, the carbon monoxide pressure, the presence of potassium iodide, the reaction time and the temperature. The optimum quantity of base for methane production is 50 mmol. Increasing the carbon monoxide pressure produces an approximately proportional increase in the gas products and a small effect on the liquid products. The reactions carried out at 360°C for 300 min show the highest yields in methane, corresponding to about 62 % of the converted carbon monoxide. Potassium iodide acts as a promotor in the reactions carried out at 360°C. The decompositions of methyl formate and methyl acetate in the presence of CO2 (CO)8 under an argon atmosphere produce relatively large amounts of methane. This shows that these esters are intermediates in the conversion of methanol to methane. The effect of reaction time was studied for the methyl acetate decomposition while for the methyl formate decomposition the effects of carbon monoxide pressure and the quantity of ester were investigated. Based on these results, a mechanism is proposed which has methyl formate and methyl acetate as intermediates.

ASSUNTO(S)

compostos de metais de transição compostos organometalicos

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