(669d) Homogeneous Catalytic Conversion of Cellulose in to 5-Hydroxymethylfurfural (HMF) Using 1-Ally-3-Methylimidazolium Chloride (AmimCl) Ionic Liquids

The consumption of petroleum has surged during the 20th century because of the rise of the automobile industry. Unfortunately, the growing demand for fossil fuel resources comes at a time of diminishing reserves of these non-renewable resources, such that the worldwide reserves of oil are sufficient to supply energy and chemicals for only about another 40 year, causing widening concerns about ?energy crisis?. Biomass can serve as a source for both energy and carbon, and being renewable it is the only sustainable source of energy and organic carbon for our industrial society.

Moreover, production of energy from biomass has the potential to generate lower greenhouse gas emissions compared to the combustion of fossil fuels, because the CO2 released during energy conversion is consumed during sub-sequent biomass regrowth..

Biomass includes various plant components, such as starch and cellulose, that are originally formed by photosynthesis. As the most abundant source of biomass , cellulose is currently regarded as a promising alternative for fossil fuels as it cannot be digested by human beings and thus its use, unlike corn and starch, will not impose a negative impact on food supplies. During the last few decades, much effort has been devoted to increasing the utilization of cellulose. However, the utilization of cellulose has been limited to lumber, fuel, textile, paper, plastic, and so on because of it is resistant to degradation. Recently, a great deal of effort has been put toward the degradation of cellulose with enzymes, mineral acids, base, and superitical water.

One of the most attractive utilization of cellulose is its direct conversion into 5-hydroxymethylfurfural (HMF), which is a versatile and key intermediate in biofuel chemistry and petroleum industry. HMF and its derivatives can replace key petroleum-based building block.

According the literature, HMF is now prepared mainly from fructose using acid as catalyst . However, fructose is so expensive that arising the production cost of HMF, thus limits the availability and use of HMF industrially. Researchers are applying their energies to converting glucose to HMF, and have acquired satisfying results. Using a system containing chromium chloride and ionic liquids, the HMF yield is up to a record high of 68%. Nevertheless, this technology is still based on food resources such as starch.. thus, it is meaningful to exploring a method that can directly convert cellulose to HMF.

Because of the high crystallinity of cellulose, the conversion of cellulose into valuable chemicals is inefficient and uneconomical. The conversion condition is always high pressure and high temperature, yet the hydrolysis is slow and complicated, producing additional by-products and increasing the cost of product purification.

Studies by Rogers et al showed that the ionic liquid (IL) 1-butyl-3-methylimidazomium chloride ([C4mim]Cl) is a powerful solvent for cellulose. Since then solubilization of cellulose as well as the reaction of cellulose in ILs has attracted much attention. A lot of researches about the reaction of cellulose in ILs have been doing all over the world, including derivatization, hydrolysis, hydrogenation and hydrogenolysis.

The hydrolysis of cellulose in ILs have been done systemly using mineral acids, solid acids as catalysts. But neither of these researches are seting HMF as a target product. An USA patient described a method to prepare HMF from cellulose in the [C4mim]Cl ILs using chromium chloride as catalyst, but it's lack of few details.

The IL, 1-ally-3-methylimidazolium chloride ([Amim]Cl) has been proved to be a good solvent in dissolving cellulose. And it has been used in the acylation of cellulose from both the high quality pulp and agricultural residue.

Recently we are carrying out an experiment on hydrolysis of cellulose into HMF using [Amim]Cl as reaction medium. Primarily experimental results shows that with chromium chloride as catalyst, the HMF yield is up to 50%. And increasing the reaction time will result the decomposition of HMF. Further studies such as the mechanism of the hydrolysis, the kinetics of the hydrolysis are underway.