ABSTRACT
Pacific Northwest National Laboratory, 902 Battelle Blvd, MS K8-93, Richland, WA
99352 chunshecao@yahoo.com
Abstract A novel gas-liquid-solid reactor based on monolith catalyst structure was developed for converting sugar alcohols to value-added chemicals such as propylene glycol. The structured catalyst was used intending to improve product selectivity. Testing at the pressure of 1,200 psig and 210°C with H2 to sorbitol molar ratio of 8.9 and a space velocity range from 0.15 to 5 hr-1 demonstrated that as high as 41 wt% of propylene glycol selectivity and 13 wt% ethylene glycol selectivity can be obtained. In addition, monolith catalysts gave higher C3/C2 ratio than that in the conventional trickle bed reactor with similar liquid hourly space velocities. Introduction Bio-based feedstocks such as glucose, sorbitol etc. can be converted into value-added chemicals such as ethylene glycol, 1,2-propylene glycol and glycerol by reacting with hydrogen over the catalysts (1-4). Such catalytic hydrogenolysis of sugar alcohols occurs in gas-liquid-solid three phase reaction systems. Conventional reactors used in this process are slurry or trickle bed reactors. In the scale-up and commercial demonstration, selectivity to desired products may be limited due to severe mass transfer limitation in the three-phase system. The selectivity to desired products are limited by the resistance in the interfaces of gas-liquid, liquid solid, and gas-solid, preventing the reactant liquid molecules from contacting the catalytic sites. Consequently, the reduced overall reaction rate requires low space velocity operation to achieve high conversion. However, long residence time may cause unwanted secondary reactions so that the selectivity is compromised. This study uses novel monolith structured catalysts in aiming to improve process productivity and selectivity. Apart from the advanced characteristics of low pressure drop, less backmixing, convenient change out of catalysts, the monolith reactor structure reduces the mass transfer limitation and potentially improves the selectivity.
