Solid Acid Catalyst For Conversion Research Articles

Efficient direct conversion of lignocellulosic biomass into biobased platform chemicals in ionic liquid-water medium

In this study, the conversion of corn straw, sorghum and cellulose into valuable chemicals (furfural, 5-hydroxymethylfurfural, levulinic acid) in different ionic liquid-water medium were investigated. Different reaction parameters such as reaction temperature, time and solvent ratio were optimized to achieve the highest conversion of biomass and selectivity of the products. Under the optimal reaction conditions (180 °C, 30 min, 1:5 ratio), 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO4) was found to display the highest efficiency which can be attributed to the acidic character of the ionic liquid. 117.4 mg levulinic acid, 11.8 mg 5-hydroxymethylfurfural and 9.4 mg furfural were obtained per g of sorghum. The results showed that 5-fold higher quantity of LA was obtained from sorghum biomass in comparison with pure cellulose. In addition, Amberlyst-15 was examined as a solid acid catalyst for conversion of cellulose in [BMIM]HSO4-water solvent system resulting in 4.6-fold increase in the quantity of levulinic acid. This study provides an alternative single step approach for production of valuable chemicals from renewable biomass.

Review: cascade reactions for conversion of carbohydrates using heteropolyacids as the solid catalysts

Conversion of biomass into renewable chemicals and fuels has received significant attention as an approach to enhance global sustainability. Biomass conversion, especially carbohydrate conversion, commonly involves cascade reactions. During these cascade reactions, various activity sites on carbohydrates may have different reactivities that enable us to control the final products through adjusting these activity sites. Heteropolyacids (HPAs), one of the major solid acid catalysts, are extensively used in biomass conversion owing to their numerous excellent physicochemical properties, such as strong Bronsted acidity, oxidizability, structural versatility, and easy design. Accordingly, this review aims to outline recent breakthroughs in obtaining platform chemicals from carbohydrates by cascade reactions involving heteropolyacid catalysts. Moreover, the relationship between the final products and the structure of heteropolyacid catalysts is discussed and insights will help us to design more efficient solid acid catalysts for conversion of biomass to more sustainable chemical products.

Lignin-based solid acid catalyst for the conversion of cellulose to levulinic acid using γ-valerolactone as solvent

Lignin was used as a carrier and loaded with ferrous sulfide to prepare a new type of solid acid catalyst for the catalytic conversion of cellulose to levulinic acid using γ-valerolactone as the solvent. The solubility characteristic of cellulose in γ-valerolactone was studied which proved that cellulose is physically soluble in γ-valerolactone. The performance of the new solid acid catalyst was evaluated in comparison with that of the commercial catalyst CMHT. The results showed that a high yield of levulinic acid (35.64%) was obtained at 185 °C in 120 min with lignin-based catalyst, when using CMHT under the same conditions, the highest yield of levulinic acid was 48.45%, which confirmed that the lignin-based solid catalyst can be used as a catalyst for the conversion of cellulose to levulinic acid. Finally, the pathway of the conversion of cellulose to levulinic acid using the new catalyst was analysed in detail for the first time. This research provides a new method for using lignin.

Design of Novel Sulfated Nanozirconia Catalyst for Biofuel Synthesis

We report on the elaboration of nanoparticulate SO42––ZrO2 solid acid catalyst for conversion of free fatty acids into biofuel. Three different morphological modifications of zirconia were prepared with the sol–gel method and compared as acid supports: polydispersed nanopowder (PNP), monodispersed nanopowder (MNP), and monodispersed nanoparticles coating (MNC). The size-selected zirconia–oxo–alkoxy (ZOA) nanoparticles of 3.6 nm diameter were prepared in a rapid micromixing reactor and either precipitated (MNP) or deposited on glass beads (MNC). The polydispersed 4/100/500 nm ZOA particles were prepared in nonparent alcohol for realization of PNP powders. The grafting of SO42– groups was realized on the three ZOA supports by wet impregnation method, and three catalysts were prepared after the subsequent drying and thermal treatment stages. The temperature of thermal treatment strongly affects the stability of the solid acid complex and serves to be an important factor of the preparation process. A strong r...

Production of levulinic acid from cellulose by hydrothermal decomposition combined with aqueous phase dehydration with a solid acid catalyst

In this paper we introduce a process to produce levulinic acid from cellulose without the use of a homogeneous acid catalyst. The process consists of 2 reaction steps: (1) non-catalytic hydrothermal decomposition of cellulose at moderate temperatures (190–270 °C) to produce organic water-soluble compounds including glucose and HMF; (2) water-soluble compounds are further reacted with a solid acid catalyst at relatively low temperatures (160 °C) to produce levulinic acid and formic acid. Unreacted cellulose can be recycled back to the first reactor for further decomposition. The cellulose hydrothermally decomposes at high initial cellulose concentrations of 29 wt% while maintaining high selectivity towards water-soluble compounds, which are levulinic acid precursors. The maximum amounts of usable water soluble organics are produced at relatively higher temperatures and shorter residence times (220 °C and 30 min). Amberlyst 70 was used as a solid acid catalyst for conversion of the water soluble organics into HMF, levulinic acid and formic acid. Amberlyst 70 has comparable activity to HCl, with a slightly lower selectivity towards levulinic acid. The maximum obtainable yield of levulinic acid we obtained was 28% of the theoretical. This study lays the grounds for further optimization to produce levulinic acid from cellulose without using homogeneous acid catalysts.

B(HSO4)3: a novel and efficient solid acid catalyst for the regioselective conversion of epoxides to thiocyanohydrins under solvent-free conditions

B(HSO4)3 was easily prepared and used as a novel and efficient solid acid catalyst for conversion of epoxides to the corresponding thiocyanohydrins under solvent-free conditions with high isolated yields. The salient features of this methodology are cheaper process, easy availability of the catalyst, versatility, and high regioselectivity of the procedure.

Use of YB(66) as monochromator crystals for soft-energy EXAFS.

YB(66)(400) crystals present a new advance in monochromator crystals suitable for use at energies below 2 keV. In this paper a comparison of their performance with that provided by the more usual beryl and quartz crystals, which cover the same energy range, is presented. In general, the YB(66) crystals are much superior; however, they do exhibit a pair of large 'crystal glitch'-type features in the 1380-1440 eV region. These fall in the Mg K-EXAFS region and so can present a serious problem in studies of this edge for a wide range of materials. An important class of materials so afflicted are magnesium-substituted aluminophosphate molecular sieves (zeolites), which are used in many applications, in particular as solid acid catalysts for conversion of methanol to hydrocarbon.