Conversion of Biomass into Chemicals over Metal Catalysts

A catalytic process for the selective formation of cis olefins would help minimize the production of unhealthy trans fats during the partial hydrogenation of edible oils. Here we report on the design of such a process on the basis of studies with model systems. Temperature programmed desorption data on single crystals showed that the isomerization of trans olefins to their cis counterparts is promoted by (111) facets of platinum, and that such selectivity is reversed on more open surfaces. Quantum mechanics calculations suggested that the extra stability of cis olefins seen on hydrogen-saturated Pt(111) surfaces may be due to a lesser degree of surface reconstruction, a factor found to be significant in the adsorption on close-packed platinum surfaces. Kinetic data using catalysts made out of dispersed tetrahedral Pt nanoparticles corroborated the selective promotion of the trans-to-cis isomerization on the (111) facets of the metal. Our work provides an example for how catalytic selectivity may be controlled by controlling the shape of the catalytic particles.

Tuning selectivity in catalysis by controlling particle shape

There is considerable interest in investigating the deoxygenation process, due to the high oxygen content of the feed-stocks used for the production of renewable fuels This review addresses studies related to the catalytic hydrodeoxygenation of two feed-stocks (a) oils with high content of triglycerides and (b) oils derived from high pressure liquefaction or pyrolysis of biomass Future research directions that could potentially bridge the existing gaps in these areas are provided

Renewable fuels via catalytic hydrodeoxygenation

Graphitic carbon nitride polymers: promising catalysts or catalyst supports for heterogeneous oxidation and hydrogenation

This critical review focuses on the origins and preparation of bio-based surfactants, defined here as non-soap, amphiphilic molecules in which the carbon atoms are derived from annually renewable feedstocks Environmental concerns and market pressures have led to greater relevance of these chemicals in commercial applications in recent years and extensive research has gone into exploring new classes of surfactants Highlighted here are examples of bio-based surfactants that are produced on an industrial scale and/or are based on abundant starting materials The trend of increasing use of renewable resources as starting materials for surfactants is introduced, followed by extensive discussion of the major classes of bio-derived hydrophobes and hydrophiles Also discussed is the status of research and development with regard to biosynthetically produced surfactants Finally, concluding remarks address the potential for new surfactant molecular structures as a result of ongoing development in the chemistry of biorefineries, ie, that the transformation of lignocellulose into fuels is likely to support the manufacturing of new bio-based coproducts (238 references)

Derivation and synthesis of renewable surfactants

Hardening of vegetable oils is reviewed from an engineering point of view. The present review focuses on kinetics of the hydrogenation and relevant transport and adsorption steps. It aims to contribute to accelerate new research to improve substantially on selectivities in general and a decrease of trans fatty acid content in particular. From a comprehensive literature review, we concluded the absence of reliable, mechanistically based kinetic rate expression. Moreover, transport limitations, both intraparticle and interfacial, cannot be excluded from the vast majority of available experimental data. Therefore, future research should focus on the development of intrinsic kinetic rate expressions, which may subsequently contribute to develop new and improved hydrogenation catalysts.

Martin J. Bouma

Papers

Heterogeneous hydrogenation of vegetable oils: A literature review