Hydrocarbons from kraft pulp pre-hydrolysis liquors in two steps using heterogeneous catalysis

Abstract

Valorizing industrial side-streams that are burnt to a low value are important to make biorefining more sustainable. In this work, hemicellulose obtained as a pre-hydrolysis liquor from kraft pulping was converted to furfural in a 19 wt% yield based on hemicellulose content in raw biomass using a beta zeolite as a catalyst. Furfural was then directly hydro-processed to yield pentane and higher hydrocarbons in 60%. It was found that a combination of Pd/C and ZSM-5 gave full hydrodeoxygenation. Depending on reaction conditions, aromatic or aliphatic compounds could be generated. By using pentane as a carrier liquid, a 100% renewable hydrocarbon stream is possible. Off gases, comprising <C₅ hydrocarbons (23% yield), could be reformed to green hydrogen to yield renewable hydrocarbon products. This way, the pulp mill is de-bottlenecked and thus can increase the production of pulp, and at the same time, another valuable product stream is generated.