Ion Exchange Montmorillonite Catalyzes Glycolysis To Prepare Methyl Levulinate

With the continuous development of society and economy, the over-increasing exploitation of non-renewable resources such as fossil fuels has aggravated the global-warming effects and polluted environment. Therefore, exploiting clean renewable energy is already in the extremely urgency. Biomass resources, the most abundant renewable resources in the world, can be converte into a variety of chemicals by different pathways. But currently the most of the biomass resources have not been used reasonably, for example biomass straw is usually discarded in the field or burned in suit. Therefore, how to utilize effectively biomass resources has been concerned by more and more people.Levulinate ester, which has good reactive activity and industrial application value, is a kind of important platform chemical and energy chemicals. Currently, there are three pathways for the synthesis of levulinate ester:1) the esterification of levulinic acid; 2) the alcoholysis of furfuryl alcohol; 3) the alcoholysis of biomass. Among these, the alcoholysis of biomass is the most promising pathway. However, the development of high efficiency catalyst is the major chanllenge for this pathway.In this thesis, various ion-exchanged montmorillonites catalyst were prepared and applied in the conversion of glucose in methanol to methyl levulinate, the main results are as follows:(1) Tin-exchanged montmorillonite was prepared by an ion exchange method and was used in the alcoholysis of glucose to methyl levulinate. The catalysts were characterized using a combination of X-ray fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy, N2 adsorption, powder X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and NH3 temperature-programmed desorption, as well as by pyridine adsorption FT-IR spectra. It was found that the tin-exchanged montmorillonite has large specific surface and the excellent catalytic performance of the tin-exchanged montmorillonite could be due to a combination of a large amount of acidic sites, together with the well balance of Lewis and Brensted acid sites on the catalyst. The yield of methyl levulinate as high as 59.7% was obtained when reacting 0.3 g glucose,0.15 g catalyst and 24 g methanol at 220? under 2 MPa N2 for 6 h. Upon recycling of the catalyst, Sn/M catalyst shows good cycle performance.(2) A series of different metal ion exchanged montmorillonite catalysts were prepared by an ion exchange method. It was found that the aluminum-exchanged montmorillonite showed the best catalytic activity and the stability. The glucose was converted completely and the yield of methyl levulinate as high as 60.7% was obtained under the optimal reaction conditions. Various characterizations were conducted on different metal ion exchange montmorillonite catalysts. The results show that, aluminum-exchanged montmorillonite has large specific surface and contains a large amount of acidic sites. It was also verified that the deposition of carbon species in pores and surface of catalyst was the main reason for catalyst deactivation. H2O2 can effectively remove the carbon species on the catalyst and the activity of the catalyst remained stable after 5 times of recycle.