Novel Catalysts for the Environmentally Friendly Synthesis of Methyl Methacrylate

Abstract

The development of a process for the synthesis of methyl methacrylate (MMA) from coal-derived syngas can alleviate the environmental hazards associated with the current commercial MMA technology, the acetone cyanohydrin (ACH) process. A three-step syngas-based process consisted of synthesis of a propionic acid, its condensation with formaldehyde, and esterification of resulting methacrylic acid (MAA) to form MMA. The first two steps, propionic acid synthesis and condensation, are discussed here. The low-temperature, low-pressure process for single-step hydrocarbonylation of ethylene to propionic acid is carried out using a homogeneous iodinepromoted Mo (CO) 6 catalyst at pressures (30-70 atm) and temperatures (150-200°C) lower than those reported for other catalysts. Mechanistic investigations suggest that catalysis is initiated by a rate-limiting CO dissociation from Mo(CO) 6 . This dissociation appears to be followed by an inner electron-transfer process of an I atom from EtI to the coordinately unsaturated Mo(CO) 5 . This homogeneous catalyst for propionate synthesis represents the first case of an efficient carbonylation process based on Cr group metals. The condensation of formaldehyde with propionic acid is carried out by acid-base bifunctional catalysts. As a result of screening over 80 catalytic materials, group V metals (V, Nb, and Ta) supported on an amorphous silica are found to be most effective. A 20% Nb/SiO 2 catalyst appears to be the most active and stable catalyst thus far. Preliminary relations among the reaction yield and catalyst properties indicate that a high surface area and a low overall surface acidity (<50 ) mol of NH 3 /g), with a high proportion of the acidity being weak (<350°C desorption of NH 3 ), are desirable. Long-term deactivation of V-Si-P, Nb-Si, and Ta-Si catalysts suggests that carbon deposition is the primary cause for activity decay, and the catalyst activity is partially restorable by oxidative regeneration.

Aluminum Triflate as a Highly Active and Efficient Nonprotic Cocatalyst in the Palladium‐Catalyzed Methoxycarbonylation Reaction

“…We are currently investigating the application of other Lewis acids to this reaction, and the investigation will also include the industrially important [3] production of methyl methacrylate (MMA) from ethene by the methoxycarbonylation product methyl propanoate, producing MMA upon condensation with formaldehyde or its dimethyl acetal. [22] Received …”

Synthesis of Methyl Methacrylate From Coal-Derived Syngas

“…RTI's experimental data serves as the design basis. In this section, the formaldehyde and propionic acid vapor condensation reaction of CH 3 F. In addition, the byproduct DEK also forms a heterogenous azeotrope with water. All of the above will contribute to the MAA product separation difficulties.…”

“…[1][2][3][4] The Research Triangle Institute (RTI)-Eastman-Bechtel research team is developing a novel three-step process for synthesis of methyl methacrylate from coal-derived syngas. This three-step process is shown schematically in Figure 1.…”

Synthesis of Methyl Methacrylate from Coal-Derived Syngas

“…The catalyst development effort at RTI for condensation of formaldehyde with propionic acid included a screening of over 81 potential catalysts (Spivey et al, 1998;Spivey et al, 1997aSpivey et al, , 1997bSpivey et al, , 1996aSpivey et al, , 1996bGogate et al, 1997), and as a result, Group V metals including vanadium, niobium, and tantalum have been shown to be active, selective, and relatively stable condensation catalysts. Over the last month, RTI has continued with follow-on characterization work on a 10-percent Nb/Si condensation catalyst, which was subjected to a long-term reaction-regeneration cycle study.…”