Production of High-Octane Fuel Components by Alkylation of Benzene with Mixtures of Ethane and Propane

摘要

The topic of the Collaborative EU-Project NEXT-GTL was the production of liquid fuels from natural gas. Novel and innovative routes were explored. Besides non-conventional routes for the catalytic formation of synthesis gas including membranes and direct catalytic conversion of methane to methanol, it encompassed the conversion of methane to aromatics followed by upgrading of the products by alkylation with ethane/propane. The aim of the upgrading discussed in this contribution was to avoid the toxicity of benzene as liquid fuel and to increase the research octane number (RON) by producing primarily ethylbenzene, n-propylbenzene and cumene as products of the alkylation reaction. Experiments were performed in a flow-type reactor at a pressure of approximately 6 bar, a reaction temperature of 350 °C and a reactant stream composed of ethane, propane and benzene. The catalyst with the best performance was found to be the bifunctional zeolite catalyst 1.7Pt-H-ZSM-5 with an n_(Si)/n_(Al) ratio of 35. The reaction yielded at least 35 wt.-% alkylaromatics after 5 h on stream. The mixture had a RON of at least 105. The RON was calculated by multiplying the molar fraction of each compound in the liquid phase with the corresponding blending RON value of the pure compound and adding the results to the final blending RON. After 70 h on stream, the yield of alkylaromatics was around 24 wt.-% with a RON of 103. The catalyst could be regenerated in hydrogen, and the long-term performance was reproduced after regeneration.