Joseph Robert Zoeller

Eastman chemical company acetic anhydride process

Abstract To the casual observer, the rhodium catalyzed carbonylation of methyl acetate would appear to be very similar to the well studied Rh catalyzed carbonylation of methanol. However, several significant differences manifest themselves upon switching from the well documented aqueous methanol carbonylation to the anhydrous methyl acetate carbonylation to acetic anhydride. These include fundamental operational changes imposed by the less favorable thermodynamics, significant changes in the by-products, and significant changes in the nature and operation of the catalyst system which, in addition to Rh and iodine, also requires the presence of both a salt and a reducing agent. The differences between the methanol carbonylation and the methyl acetate carbonylation can be explained via a mechanistic study which, based primarily upon high pressure kinetic and infrared data, leads to a unique mechanistic proposal. The key technical breakthroughs, how they led to a successful commercial process, and comparisons of the methyl acetate carbonylation to the methanol carbonylation will be discussed in detail. A brief historical development of the process is included.

Synthesis of methyl methacrylate by vapor phase condensation of formaldehyde with propionate derivatives

Abstract The gas phase condensation of formaldehyde with propionic acid, propionic anhydride, and methyl propionate was studied over a series of V-Si-P catalysts of varying atomic ratios. Propionic anhydride gave the maximum yield of methacrylic acid (56%, based on formaldehyde fed to the reactor) at 300°C, 2 atm, 290 cc g−1 h−1 and a stoichiometric anhydride/ formaldehyde ratio of 2:1. This yield was obtained for the optimum V-Si-P catalyst, which had an atomic ratio of 1:10:2.8. This is the highest yield reported to date for the heterogeneous catalytic condensation of propionic anhydride with formaldehyde. A parameter called the q-ratio has been defined to correlate condensation yields to catalyst acid-base properties. Higher q-ratios (0

Molybdenum catalyzed ethylene carbonylation. II. Spectroscopic investigation of the reactions and equilibria of molybdenum hexacarbonyl and molybdenum halocarbonyls under reaction conditions

Abstract A surprisingly efficient carbonylation of ethylene to yield propionic anhydride and propionic acid using halide promoted Mo(CO)6 catalysts has been recently reported in the literature. Although the earlier report included detailed kinetics and a unique mechanistic interpretation involving a metalloradical process, the spectroscopic examination, which played an important role in clarifying the reaction mechanism, was only described qualitatively. This report describes the in situ infrared spectroscopic investigation of the chemistry of the molybdenum carbonyl catalysts in greater detail. Emphasis will be on the spectroscopic examinations of the equilibria of Mo(CO)6 and the molybdenum halocarbonyls, the oxidation of Mo(0) with alkyl halides, and in situ regeneration of the active catalyst under reaction conditions. As part of this investigation, a general method for the determination of equilibrium constants for reactions involving infrared active species using attenuated total reflectance technique, ATR, is described wherein neither the extinction coefficient nor the effective pathlength are known with certainty. The method is demonstrated using the equilibrium between Mo(CO)6 and Mo(CO)5I− as an example.

Molybdenum catalyzed carbonylation of ethylene to propionic acid and anhydride

Abstract We have discovered a low pressure and low temperature process for the single step conversion of ethylene and carbon monoxide to either propionic acid or anhydride utilizing surprisingly active, inexpensive Cr group based catalysts which operate at very high rates under low-to-moderate pressures (30–70 atm) and temperatures (150–200°C). Mechanistic investigations of the Mo based process, which is clearly the most active metal of the group, imply that catalysis is initiated by a rate limiting CO dissociation from Mo(CO)6. This dissociation appears to be followed by a process which ultimately transfers an I atom from EtI to the coordinatively unsaturated Mo(CO)5, probably via an inner sphere, electron transfer process. Subsequent reaction of the resultant ethyl radical with Mo(CO)6 probably generates very reactive odd electron Mo species which are capable of rapid catalysis via classical olefin carbonylation mechanisms. This discovery represents the first case of an efficient carbonylation process based on the Cr group metals and a unique method for initiating carbonylation catalysis. A general description of this process and the mechanistic proposal, which is based on detailed kinetics, spectroscopy and model reactions, will be presented.

Molecular Active Sites in Heterogeneous Ir-La/C-Catalyzed Carbonylation of Methanol to Acetates.

We report that when Ir and La halides are deposited on carbon, exposure to CO spontaneously generates a discrete molecular heterobimetallic structure, containing an Ir-La covalent bond that acts as a highly active, selective, and stable heterogeneous catalyst for the carbonylation of methanol to produce acetic acid. This catalyst exhibits a very high productivity of ∼1.5 mol acetyl/mol Ir·s with >99% selectivity to acetyl (acetic acid and methyl acetate) without detectable loss in activity or selectivity for more than 1 month of continuous operation. The enhanced activity can be mechanistically rationalized by the presence of La within the ligand sphere of the discrete molecular Ir-La heterobimetallic structure, which acts as a Lewis acid to accelerate the normally rate-limiting CO insertion in Ir-catalyzed carbonylation. Similar approaches may provide opportunities for attaining molecular (single site) behavior similar to homogeneous catalysis on heterogeneous surfaces for other industrial applications.

Synthesis of vinyl acetate monomer from synthesis gas

Abstract Previous attempts to synthesize vinyl acetate monomer (VAM) from synthesis gas involve routes that require a costly recycle of acetic acid through a carbonylation reactor. Two new routes to VAM from synthesis gas that avoid this acetic acid recycle have been investigated. One of these new routes synthesizes VAM from acetic acid via the intermediacy of ketene. Ketene is hydrogenated to acetaldehyde, and the acetaldehyde is reacted directly with ketene to produce VAM. The second route synthesizes VAM from the carbonylation of dimethyl ether to acetic anhydride followed by reaction of the acetic anhydride with acetaldehyde in a reactive distillation column to produce VAM and acetic acid. The co-produced acetic acid is hydrogenated to form the acetaldehyde required in the reactive distillation.

Alternate fuels and chemicals from synthesis gas: Vinyl acetate monomer. Final report

There has been a long-standing desire on the part of industry and the U.S. Department of Energy to replace the existing ethylene-based vinyl acetate monomer (VAM) process with an entirely synthesis gas-based process. Although there are a large number of process options for the conversion of synthesis gas to VAM, Eastman Chemical Company undertook an analytical approach, based on known chemical and economic principles, to reduce the potential candidate processes to a select group of eight processes. The critical technologies that would be required for these routes were: (1) the esterification of acetaldehyde (AcH) with ketene to generate VAM, (2) the hydrogenation of ketene to acetaldehyde, (3) the hydrogenation of acetic acid to acetaldehyde, and (4) the reductive carbonylation of methanol to acetaldehyde. This report describes the selection process for the candidate processes, the successful development of the key technologies, and the economic assessments for the preferred routes. In addition, improvements in the conversion of acetic anhydride and acetaldehyde to VAM are discussed. The conclusion from this study is that, with the technology developed in this study, VAM may be produced from synthesis gas, but the cost of production is about 15% higher than the conventional oxidative acetoxylation of ethylene, primarily due to higher capital associated with the synthesis gas-based processes.

Acid-base properties, deactivation, and in situ regeneration of condensation catalysts for synthesis of methyl methacrylate

Condensation reaction of a propionate with formaldehyde is a novel route for synthesis of methyl methacrylate (MMA). The reaction mechanism involves a proton abstraction from the propionate on the basic sites and activation of the aliphatic aldehyde on the acidic sites of the catalyst. The acid-base properties of ternary V-Si-P oxide catalysts and their relation to the NWA yield in the vapor phase condensation of formaldehyde with propionic anhydride has been studied for the first time. Five different V-Si-P catalysts with different atomic ratios of vanadium, silicon, and phosphorous were synthesized, characterized, and tested in a fixed-bed microreactor system. A V-Si-P 1:10:2.8 catalyst gave the maximum condensation yield of 56% based on HCHO fed at 300{degrees}C and 2 atm and at a space velocity of 290 cc/g cat{center_dot}h. A parameter called the ``q-ratio`` has been defined to correlate the condensation yields to the acid-base properties. The correlation of q-ratio with the condensation yield shows that higher q-ratios are more desirable. The long-term deactivation studies on the V-Si-P 1: 10:2.8 catalyst at 300{degrees}C and 2 atm and at a space velocity of 290 cc/g cat{center_dot}h show that the catalyst activity drops by a factor of nearly 20 over a 180 h period. The activity can be restored to about 78% of the initial activity by a mild oxidative regeneration at 300{degrees}C and 2 atm. The performance of V-Si-P catalyst has been compared to a Ta/SiO{sub 2} catalyst. The Ta- catalyst is more stable and has a higher on-stream catalyst life.