在本文中,在大气压下,用磷酸催化1,2-丙二醇(PG)和二甘醇(DEG)液化玉米秸秆纤维素的实验。研究了反应时间对多元醇液化过程中纤维素结构变化的影响,旨在了解酸催化多元醇作用下纤维素液化反应的机理。发现随着反应时间的延长,液化产率呈先增加后降低的趋势,并在150分钟时达到最高(99.34%)。在提高液化产量的阶段,纤维素被降解并转化为葡萄糖,然后用PG/DEG将其转化为大量的糖苷。这些糖苷进一步转化为低分子量(LMW)物质,如碳氢化合物,酸,酒精,酯类,酮,和醚。此时,生物燃料中含有70%-85%碳数小于25的化合物和5%-10%碳数大于25的化合物。随着反应时间的延长(150分钟后),由纤维素降解形成的大量不稳定自由基可以彼此结合或与PG/DEG提供的氢原子结合以产生相对稳定的大分子物质。也就是说,多分散性(Mw/Mn,在此阶段生成的生物燃料的缩写-=1.28)不再减少。然而,240分钟产生的液化残渣发生了本质变化,与液化初期产生的液化残渣完全不同。总之,本文通过研究多元醇液化过程中的结构变化,揭示了纤维素的部分反应过程,为探索纤维素液化机理奠定了理论基础。
In this paper, the experiment of cellulose from corn stalk using 1, 2-propylene glycol (PG) and diethylene glycol (DEG) liquefaction catalyzed by phosphoric acid at atmosphere pressure was carried out. The effect of reaction time on the structural changes of cellulose in the liquefaction process of polyhydric alcohols was investigated, aiming at understanding the mechanism of cellulose liquefaction reaction under the action of acid catalyzed polyhydric alcohols. It was found that the liquefaction yield increased first and then decreased with the extension of reaction time, and reached the highest at 150 min (99.34 %). In the phase of increasing liquefaction yield, cellulose was degraded and translated into glucose, which was then converted into plenty of glycosides with PG/DEG. These glycosides were further converted into low molecular weight (LMW) substances such as hydrocarbons, acids, alcohols, esters, ketones, and ethers. At this time, the
biofuel contained 70 %-85 % compounds with carbon number less than 25 and 5 %-10 % compounds with carbon number more than 25. As the prolongation of reaction time (after 150 min), quantities of unstable free radicals formed by cellulose degradation could combine with each other or with hydrogen atoms provided by PG/DEG to produce relatively stable macromolecular substances. That is, the polydispersity (Mw/Mn, abbreviated Ð = 1.28) of the generated
biofuel at this stage no longer decreased. However, liquefaction residue produced at 240 min had changed essentially, which was completely different from the liquefaction residue produced in the early stage of liquefaction. In conclusion, this paper revealed the partial reaction process of cellulose by studying the structural changes in the liquefaction process of polyhydric alcohols, which laid a theoretical foundation for exploring the liquefaction mechanism of cellulose.