(600j) Effect of Operating Conditions On Selectivity of Propylene From Bio-Ethanol Dehydration Using SAPO-34 Catalyst

In recent years, with the global warming problem and the energy crisis, the production of chemicals from renewable resources has been paid more attention. Light olefins (ethylene and propylene); one group of the important chemicals, can be produced from renewable resources as well. Recently, there have been a few reports on the production of ethylene from bio-ethanol that is a renewable resource, using a silicoaluminophosphate zeolite (SAPO-34) catalyst through the catalytic dehydration process. The suitable temperature for the highest production of ethylene is 350 ^oC, after which it decreases. However, the selectivity to propylene at high reaction temperatures and low space velocity had not yet been investigated. In this work, the objective was therefore to study the effect of using SAPO-34 in the catalytic conversion of bio-ethanol to light olefins at various operating conditions, aiming to find the optimal condition for the high propylene production. The reaction temperature and liquid hourly space velocity (LHSV) were varied in the range of 350 ^oC to 500 ^oC and 0.2 h^-1 to 1.0 h^-1, respectively. As a result, the reaction temperature and LHSV had the influences on catalytic activity. Low temperature or high LHSV are highly effective for the production of ethylene whereas low temperature or low LHSV are highly effective for the production of C₄₊ products. The reaction temperature of 400 ^oC and the LHSV of 0.5 h^-1 were found to be the suitable conditions for a high production of propylene with 92.5% ethanol conversion and 12.6% propylene selectivity. The reaction temperature and the LHSV also affected to the coke formation on the catalyst. The amount of coke increased with the increase of reaction temperature and the decrease of LHSV.