I n d . E n g . C h e m . Res. 1987,26, 1269-1275
1269
Methyl Formate from Methanol Oxidation over Coprecipitated V-Ti-0 Catalysts Enrico Tronconi, Ahmed S. Elmi, Natale Ferlazzo, and Pi0 Forzatti* Dipartimento di Chimica Zndustriale ed Zngegneria Chimica "G. Natta" del Politecnico, Piazza L. da Vinci 32, 1-20133 Milano, Italy
Guido Busca Zstituto di Chimica, Facoltci di Zngegneria dell' Uniuersitd, Padiglione D, 1-16129 G e n o m , Italy
Paolo Tittarelli Stazione sperimentale per i combustibili, 1-20097 San Donato Milanese, Italy
The activity of coprecipitated V-Ti oxide catalysts calcined at 600 "C in the oxidation of methanol t o methyl formate has been studied. The catalysts have been characterized by XRD, surface area measurements, UV-visible diffuse reflectance, ESR, FT-IR, and adsorption of probe molecules. Activity tests have shown that there is an optimum V content for the selectivity to methyl formate, which may result from a suitable balance between oxidizing properties and surface area of the catalysts. T h e effects of the main operating variables on the conversion and product distribution have been investigated in order t o assess the feasibility of this oxidative route to methyl formate. T h e results have been rationalized according to a reaction scheme involving primarily a consecutive oxidation of methanol t o formaldehyde and then t o methyl formate. A comprehensive survey of possible methyl formate
(MF) applications has been recently published by Roeper (1984), where it is pointed out that methyl formate will likely gain interest as a key intermediate if syngas and methanol become increasingly competitive feedstocks for the chemical industry. At present, methyl formate is produced on a large scale as an intermediate in the synthesis of formic acid and formamides. However, this versatile ester has potential for a future more extensive chemical utilization, which may include, e.g., the synthesis of pure carbon monoxide, methanol, dimethyl carbonate, acetic acid (by isomerization), and ethylene glycol via methyl glycolate. In fact, all of these methyl formate based processes would either avoid the use of high-purity carbon monoxide or operate a t milder conditions than conventional processes. Current technology for the production of methyl formate involves carbonylation of methanol in a homogeneous liquid phase in the presence of basic catalysts, typically sodium methoxide, a t 70-80 "C under moderate to high CO pressures. Processes based on such a scheme were originally developed by BASF (1925) and later by Leonhard Process Co. (1979). Productivities of about 800 g/(L h) have been achieved. An alternative route to methyl formate has been recently proposed by Mitsubishi Gas Chemical, involving the endothermic gas-phase dehydrogenation of methanol over Cu-based catalysts a t 190 "C and atmospheric pressure (Ikarashi,1980). Space time yields up to 3000 g/(L h) have been claimed for this process. A number of papers concerning this reaction have appeared in the scientific literature in the last few years (Morikawa et al., 1984; Ai, 1984; Tonner et al., 1984; Cant et al., 1985). Little work has been published so far on the gas-phase oxidative route to methyl formate starting from methanol, 2CHsOH + 0 2 HCOOCH, + 2H20
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This reaction was studied by Ai (1982) over various Moor W-based oxide catalysts. In previous papers (Forzatti et al., 1987; Busca et al., 1987) we have reported that such
* To whom correspondence should be addressed.
a reaction occurs along with the formation of formaldehyde a t low temperatures (
