Wei Hua Yu

Recent Advances in Catalytic Conversion of Glycerol

The article underlines and discusses the state-of-the-art accomplishments in the catalytic conversion of glycerol (1,2,3-propanetriol) to fuels and value-added chemicals in the past five years (2008–2012). The reactions include steam reforming, aqueous-phase reforming, hydrogenolysis, oxidation, dehydration, esterification, etherification, carboxylation, acetalization, and chlorination. Typical products are hydrogen, propanediols, dihydroxyacetone, glyceric acid, acrolein, glyceride, polyglycerol, glycerol carbonate, acetals, ketals, and epichlorohydrine. Recent studies on the catalysts, reaction conditions, and possible pathways are primarily discussed. They indicate that major breakthroughs are achieved by the use of multifunctional catalysts, process intensification and integrated reactions. Literature survey suggests that future work on the catalytic conversion of glycerol for commercial goals particularly requires new catalysts, innovative reactor engineering, and close multidisciplinary partnership.

Novel hydrothermal carbonization of cellulose catalyzed by montmorillonite to produce kerogen-like hydrochar

Abstract The conversion of cellulose to petroleum-like fuel is a very challenging yet attractive route to developing biomass-to-fuel technology. Many attempts have been made in liquefaction, pyrolysis and gasification of cellulose to produce fuels or intermediate chemicals. Previous studies indicate that these processes are tough. Hence, the present work is concerned with the development of new technologies for the conversion of cellulose into materials which are analogies to the precursor of petroleum. Montmorillonite-catalyzed hydrothermal carbonization of microcrystalline cellulose for the production of kerogen-like hydrochar under mild conditions was investigated. It was revealed that the hydrothermal carbonization of microcrystalline cellulose alone resulted in hydrochar with type III kerogen-like structure, whereas in the presence of montmorillonite, the hydrothermal carbonization of microcrystalline cellulose yielded a hydrochar-mineral complex, of which the isolated organic fraction was oil-prone type II kerogen-like structure. Results suggested that further improved montmorillonite-aided biomass conversion to more oil-prone kerogen-like solid products could be an alternative efficient route to obtain biofuel and chemicals.

Modification of inorganic porous materials as gene vectors: an overview

Abstract The use of porous materials as gene vectors is becoming more important and striking than their traditional uses in catalysis and separation. This article highlights recent advances in the modification of typical inorganic porous materials which are specifically and necessarily conducted for their uses as gene vectors. Literature survey indicates that carbon nanotubes, layered double hydroxides, mesoporous silica and carbon nanoparticles and the related hierarchical materials have received particular attention in recent years. Though these inorganic porous materials have high surface area and porosity, to choose surface modification judiciously is often required for improving their performances in the loading of genes, targeted delivery and controlled release of genes. Major modification methods are adsorption or grafting of other molecules onto the surface of these inorganic porous materials. In addition, modification by adding magnetic nanoparticles to the porous materials has been investigated. Nevertheless, thus far most studies on the modification have aimed merely at the improvement of the loading, the delivery and the release of gene. Exact biocompatibility and in vivo therapy effectiveness remains elusive and are still in question.

Catalytic Thermochemical Processes for Biomass Conversion to Biofuels and Chemicals

Abstract Biomass is the most abundant and biorenewable resource with great potential for sustainable production of chemicals and fuels. Thermochemical conversion technologies (pyrolysis, gasification and hydrothermal liquefaction) are a promising option for transforming biomass feedstocks into liquid oils and chemicals. In the article, for the thermal process of biomass for biofuels and chemicals, the effect of reaction conditions, reactors, solvents and catalysts on the yield and distribution of the products are reviewed. Fast pyrolysis of cellulose is primarily conducted over catalysts with proper acidity/basicity and has undergone many pilot tests. Gasification is typically conducted over supported noble metal catalysts and has been profiled as being CO2-neutral, having a high potential to provide power, chemicals and fuels. Catalytically hydrothermal liquefaction of biomass produces a very complex mixture of liquid products; therefore, novel technology for separation and extraction of downstream products from hydrothermal liquefaction of lignocellulosic biomass need to be developed.

Immobilization of lipase onto aminopropyl-functionalized MSU-H type mesoporous silica and esterification

Candida rugosa lipase (CRL) was immobilized on an aminopropyl-functionalized MSU-H type mesoporous silica (AFMS) through physical adsorption and a covalent cross-linking. It was evaluated as a class of biocatalysts in the esterification of conjugated linoleic acid (CLA) isomers with ethanol. AFMS materials with varied content of aminopropyl were prepared by a simple co-condensation at near neutral pH condition. Introduction of aminopropyl chains and CRL molecules onto the AFMS supports was confirmed by Fourier transform infrared (FT-IR) spectra. CRL was immobilized on the AFMS through electrostatic and covalent interactions. The covalently cross-linked CRL gave a loading amount of 34.3mg CRL/g-support and a hydrolytic activity of 2471.5U/g-catalyst. It exhibited high operational stability and remained 23.9-27.5% of total esterification in 32 h consecutive four runs in the esterification of CLA with ethanol. Moreover, the immobilized CRLs catalyzed 2.8-3.8 times of esterification of cis-(c)9, trans-(t)11-CLA faster than that of t10, c12-CLA.

PREPARATION OF ORGANO-MONTMORILLONITES AND THE RELATIONSHIP BETWEEN MICROSTRUCTURE AND SWELLABILITY

Hydrophobicity, swellability, and dispersion are important properties for organo-montmorillonites (OMnt) and have yet to be fully characterized for all OMnt configurations. The purpose of the present work was to examine the preparation of OMnt from the reaction of Ca2+-montmorillonite (Ca2+-Mnt) with a high concentration of surfactant and to reveal the relevant properties of hydrophobicity and dispersion of the resultant OMnt. A series of OMnt samples were prepared using a small amount of water and cetyltrimethylammonium bromide (CTAB) with a concentration more than the CTAB critical micelle concentration (CMC). The relationship between OMnt microstructure and the hydrophobicity and swellability properties was investigated in detail. The resulting OMnt samples were characterized using powder X-ray diffraction patterns (XRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric and differential thermogravimetry (TG-DTG), water contact angle tests, swelling indices, and transmission electron microscopy (TEM). The addition of CTAB and water in the OMnt preparation affected the OMnt microstructure and properties. An increase in CTAB concentration led to a more ordered arrangement of cetyltrimethylammonium (CTA+) cations in the interlayer space of the OMnt and a large amount of CTA+ cations on the outer surfaces of the OMnt. The swelling indices and the water contact angles of OMnt samples depended on the distribution of the CTAB surfactant on OMnt and the orientation of the surfactant hydrophilic groups on the inner and on the outer surfaces of OMnt. A maximum swelling index of 39 mL/g in xylene was achieved with an average water contact angle of 62.0° ± 2.0° when the amount of CTAB added was 2 times the cation exchange capacity (CEC) of Mnt and the lowest water to dry Mnt mass ratio was 3 during the preparation of OMnt samples. The platelets of OMnt aggregated together in xylene by electrostatic attraction and by hydrophobic interactions.