Hydrolysis Of Glucose Solutions Over Solid Acid Catalyst

Levulinic acid (LA), which can be prepared from biomass, is an important chemical raw material whose applications will be wider and wider in various industries. So, LA can become a new platform chemical. But the traditional preparation processes of LA from biomass using liquid acid catalysts such as hydrochloric acid and sulfuric acid. Since these liquid acids are corrosive and produce a large amount of waste, replacement of the liquid catalysts with solid acid catalysts is desirable for developing environmentally benign process.In this work, the hydrolysis behaviors of glucose to LA over three types solid acid catalysts which were more than 60 catalysts included 12-tungstophoric acid catalysts, niobic acid catalysts and zeolite catalysts were studied respectively.12-tungstophoric acid, a Keggin-type heteropolyacid, is a strong BrOnsted acid, which is used widely as homogeneous and heterogeneous acid catalysts. In this system, the acidic cesium salts of H3PW12O40 and the supported systems of H3PW12O40 were studied. For LA formation, the catalyst activity of the CS2 5H0.5PW12 is the highest because of its abundant pore structures, high surface area and strong acidity.Niobic acid is a special solid acid. Its surface acidity is strong in spite of the water content. So, it is likely to keep stability catalytic activity in the acid-catalyzed reactions which have water jion or release. In this system, the water-washed niobic acid, acid-washed niobic acid and niobic acid for phosphoric acid-treated were studied. The results indicate that the intermediate product 5-hydroxymethyl-2-furaldehyde (HMF) selectivity of niobic acid is high and the increasing surface acidity of niobic acid could not enhance activity of the catalyst for the LA formation.Zeolites are favorable solid acid catalysts. In this system, the hydrolysis behaviors of glucose to LA over ZSM-5, Hβand ZRP were studied respectively. Of the four catalysts tested, the ZRP catalyst offered the highest LA yield. For ZRP zeolite with calcinations temperature of 550℃, when the reaction was conducted at aninitial glucose concentration of 10g/L and catalyst loading which was represented by the glucose to catalyst ratio (weight ratio) of 1.2 within a 1L stirred reactor with impeller speed of 300rpm at 180℃ for 8h, the LA yield was 39.79% which is close to that from glucose to LA over hydrochloric acid.Consequently, for this reaction system, ZRP zeolite is hopefully to be used as candidate of the hydrolysis reaction catalyst. Furthermore, this paper offers basic data for a further study.