Cellulosic Biomass Takes Over

The basic processes for converting cellulosic biomass to transportation fuels are already in widespread commercial use. Conversion typically starts with a pretreatment step, which makes cellulose from biomass feedstocks more accessible to enzymatic breakdown. Various enzymes then hydrolyze the cellulose into its component sugars, and microbes turn those sugars into fuels such as ethanol. Patenting in these areas frequently focuses on process improvements.

A 2013 patent application (WO 2013083816) filed by researchers at Shell Oil provides an example. In this case, the emphasis is on the pretreatment stage. Shell researchers used tertiary polyamide additives such as poly­vinyl­pyrrolidones and poly(alkyl oxazolines) to enhance the breakdown of cellulosic biomass into its component sugars.

In one example from this patent, the researchers ground up and homogenized wheat straw with and without a polyvinylpyrrolidone additive. They then used enzymes to hydrolyze washed and unwashed samples of this mixture. They measured the extent of hydrolysis by looking at the amount of glucose produced.

The researchers found that the additive improved cellulose conversion by about 50%. Interestingly, they saw improvements in both the washed and unwashed samples. Because washing might be expected to remove the water-soluble pyrrolidones, the results suggest that the additive might be interacting directly with the biomass in some way.