Recent Patents on Catalysis (v.2, #1)

Editorial by Shaobin Wang (1-1).

Heterogeneous Catalysis by Gold-based Bimetallic Catalysts by Like Ouyang, Guo-Jin Da, Jun Ni, Jing Xu, Yi-Fan Han (2-46).
This critical review summarizes recent advances on the preparation, characterization and application of Aubasedbimetallic Au-M catalysts. Particularly bimetallic Au-Pd, Au-Pt and Au-Ag catalysts have been emphasized. Thediversity of the structure and combination of these bimetallic Au-M catalysts leads to various catalytic performances in,i.e., oxidation, hydrogenation, electrocatalytic, and photocatalytic reactions. The promotional effects of Au have been discussedby its electronic and geometric modifications of active metals. Efforts on controlling the structure (morphology,particle size and growth of crystalline) of supported bimetallic Au-M catalysts via advanced synthetic approaches havebeen elaborated. An overview on the challenges and opportunities for future research toward the understanding of catalyticchemistry of gold-based bimetallic systems has also been presented along with the descrption of few of the recentpatents.

Cinchona Alkaloid-Catalyzed Stereoselective Carbon-Carbon Bond Forming Reactions by Srinivasarao A. Babu, Ramasamy V. Anand, Sripada S.V. Ramasastry (47-67).
This review provides insights into the patents available on one of the subfields of organocatalytic reactions,specifically, the Cinchona alkaloids-based organocatalytic reactions, involving asymmetric C-C bond construction. Someof the very important achievements in the asymmetric carbon-carbon bond formation by employing the Cinchona alkaloids-based organocatalysts, one of the privileged classes of asymmetric catalysts, have been accentuated. The Cinchonaalkaloids-based enantio- and diastereoselective syntheses of a range of amino acid derivatives, bioactive molecules andvarious synthetic intermediates with high efficiency are also highlighted.

Dimethyl Ether Synthesis Catalysts, Processes and Reactors by Grigore Bozga, Ioan T. Apan, Raluca E. Bozga (68-81).
The paper is reviewing the patents and journal papers treating catalysis and engineering issues involved in thedimethyl ether (DME) production from synthesis gas. The necessary catalysts include components active for the two reactionsdefining this process: carbon oxides hydrogenation to methanol and methanol etherification to DME respectively.For the first reaction, amongst the dozens of catalytic materials proposed, the largest utilization has the classical methanolsynthesis catalyst Cu-ZnO-Al<sub>2</sub>O<sub>3</sub>, sometimes modified with ingredients contributing to the increase of the copper dispersionand stability. Good activity and selectivity for methanol etherification have the solid acids with moderate acidity ( &#947;-Al<sub>2</sub>O<sub>3</sub>, zeolites, mesoporous materials etc.). An important challenge in the formulation of the bi-functional catalyst and thereactor design is the prevention or limitation of deactivating phenomena: copper sintering, coking of acidic componentsand metal ions migration. Particularly, a good temperature control is necessary, due to the important overall process exothermicity.Demonstration plants having capacities up to 100 t DME/day, based on tri-phase slurry reactors or jacketedmulti-tubular reactors, are already in successful operation. An important drawback of the one-step DME synthesis processis the formation of CO<sub>2</sub> as secondary product, difficult to separate from DME mixture. Patented technologies are based onseparation by extraction with selective solvents or by refrigeration and distillation. Efficient and environmentally friendlydesign solutions are integrating the DME synthesis line with hydrocarbon reforming units, recycling and valorizing CO<sub>2</sub>byproduct. Studies are also in progress, aiming to develop technologies for DME synthesis by CO<sub>2</sub> hydrogenation.

Ru<sup>3+</sup>-exchanged supported 12-tungstophosphoric acid was synthesized, characterized and used for solvent-freeliquid phase aerobic oxidation of styrene under mild reaction conditions. The present catalyst gives 100 &#37; conversion ofstyrene with &#62;99 &#37; selectivity for benzaldehyde. The catalyst can also be regenerated and reused.