Production of bio-ethene and propene: alternatives for bulk chemicals and polymers

There is an increasing trend to use bio-polyethene and bio-polypropene in Europe. However there is at present very limited production capacity available for producing the base chemicals that are used in polymerization processes. Therefore a production route for green ethene, propene and 1,3-butadiene is evaluated on a pilot plant scale starting from triglyceride and fatty acid based biomass. The first step consists of removing suspended solids, solubilized metals and phosphorus from the feedstock. The next step is catalytic hydrodeoxygenation (HDO) of the purified product to reduce oxygen to less than 0.1 wt%. Finally the HDO product is cracked into light olefins in a steam cracking pilot plant. For a coil outlet temperature of 835 degrees C and a steam dilution of 0.45 kg kg(-1) the product yields amount to 38 wt% ethene, 20 wt% propene and 7.5 wt% 1,3-butadiene. This is significantly higher than the yields that are obtained when cracking classical fossil based naphtha under similar process conditions. Moreover, the fouling tendency of the renewable feed is also a factor of 2 smaller than that for naphtha. The pilot plant data have been used to scale up to a commercial scale steam crackers by applying a validated fundamental kinetic model, indicating the high potential of this route for producing green high value chemicals with a 20% reduction in CO2 emissions as compared to a naphtha cracker.