From medium chain fatty alcohol to jet fuel: Rational integration of selective dehydration and hydro-processing

摘要

Middle chain fatty alcohols, which can be easily obtained from bio-synthesis and fatty acid hydro-treatment, were used as a renewable resource to produce alternative jet fuels by rational integration of selective dehydration and hydro-processing. Various catalysts such as ZSM-22, Al-MCF and ZSM-5 with different textural and acidic properties were tested in the dehydration step. It was found that the structural and acidic properties have significant influences on the dehydration performance and product distribution. After Pt introduction, the fatty alcohols can be converted into paraffins with different isomerization degrees. The different integrations of dehydration and hydro-processing steps resulted in different medium chain fatty alcohol to jet fuel production processes. Three different production processes, one-step hydro-isomerization over Pt/ZSM-22, dehydration (Al-MCF)/hydro-isomerization (Pt/ZSM-22) and dehydration (ZSM-22)/hydro-processing (Pt/MCF) were developed and tested. The dehydration (Al-MCF)/hydro-isomerization (Pt/ZSM-22) process, which provides the highest iso-paraffin yield, was used for conversion of a commercially available alcohol mixture in a pilot scale reactor. The product obtained from such pilot scale experiment had a freezing point of -60 degrees C and met the requirements of ASTM 7566 specification except for density.