Study Of Dehydration Of Xylose To Furfural With Green Technics

Dehydration of xylose to furfural is a acid catalyzed reaction, and the conventional catalyst is liquidacid which can cause a series of problems. This paper has shown that liquid acid could be replaced bysolid acid, high temperature water and acidic ionic liquid. Solid acid catalysis process coupled withsupercritical fluid extraction was studied preliminaryly and production technics of furfural from xylosewith high temperature water and ionic liquid was investigated. The results are as follows:Three solid acids （SO₃H-SBA-15、SO₃H-G and SO₃H-CNT） were prepared, and used to catalyzedehydration reaction of xylose. It has shown that all of the three solid acid could reach xylose conversionas high as95%, only did SO₃H-SBA-15get a higher selectivity of furfural with a yield69%. In the process ofconversion of xylose to furfural with SO₃H-SBA-15coupled with supercritical carbon dioxide extraction,xylose conversion is93%and furfural yield is36%.Compared to the catalytic effect of high temperature water medium and liquid acid and solid acid, ithas shown that high temperature water could replace liquid acid or solid acid used in the reaction ofxylose to furfural. The effect of reaction temperature, residence time, and initial xylose concentration ondehydration reaction was investigated, which indicated that the best yield of furfural78%was got on theoptimal conditions: reaction200℃，residence time3h, initial xylose concentration10%.A acidic ionic liquid （IL） with a phase-separation property was prepared, which held the advantagesof good mass-transforming of liquid acid and easy separation of solid acid. The catalytic property of IL isbetter than that of liquid acid and solid acid in the dehydration of xylose to furfural. The effect of reactiontemperature, residence time, and dosage of IL catalyst on the dehydration reaction was investigated,which indicated that the best yield of furfural was70%at the following conditions: reaction temperature160℃，residence time3h, n（xylose）:n（IL）=5:1. The recycling of IL was studied, and the result indicatedthat catalytic activity of IL decreased significantly after three runs. So there is a requirement to improve ILin the next work.