ABSTRACT
Abstract In this paper we report a method for the rapid optimization of process conditions for a model reaction (selective hydrogenation of phenol to cyclohexanone over Pd/C in liquid phase), which in general could be applied to any reaction. Our goal is to optimize the process conditions that would maximize the yield of cyclohexanone within the reaction constraints. The variables examined include temperature (120 °C to 150 °C), pressure (15-30 bar), and NaOH concentration (410-820 ppm w/w). The liquid phase hydrogenation of phenol was conducted in a well-stirred autoclave at a constant hydrogen pressure in the absence of mass-transfer limitations. The number of experiments was minimized using the two-level factorial method. Further, conducting these experiments in two independent reactors in parallel shortened the optimization time. The activity and selectivity of the reaction was followed using hydrogen-uptake and product analysis by gas chromatography. A maximum cyclohexanone yield of 73% was obtained at 135 °C, and 22.5 bar with 615 ppm NaOH. Introduction Three-phase slurry reactors are commonly used in fine-chemical industries for the catalytic hydrogenation of organic substrates to a variety of products and intermediates (1-2). The most common types of catalysts are precious metals such as Pt and Pd supported on powdered carbon supports (3). The behavior of the gas-liquid-slurry reactors is affected by a complex interplay of multiple variables including the temperature, pressure, stirring rates, feed composition, etc. (1-2,4). Often these types of reactors are operated away from the optimal conditions due to the difficulty in identifying and optimizing the critical variables involved in the process. This not only leads to lost productivity but also increases the cost of down stream processing (purification), and pollution control (undesired by-products).
