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With the overview of different kinds of phenol synthesis routes, dehydrogenation of cyclohexanone to phenol under sub-critical water condition using Pt, Pd, Rh, Ru and Re immobilized heterogeneous catalysts have been reported. Surface properties and characterizations of the catalysts were done. Binding of metal on a support and their relationship with zeta potential (ζ) and their effect on catalytic activity are discussed. Importance of sub-critical water reaction conditions in terms of thermodynamic favourability and phase equilibrium are evaluated through ASPEN simulator. Based on the results obtained, possible reaction pathways for the formation of product and the by-products are illustrated. The feasibility of a metal acting as a dehydrogenation catalyst according to M0/MII (E0) couple is also explained.

Abstract Removal of trace olefins from aromatic liquids was investigated on UZM-8 and MCM-22, which are the family of MWW zeolites. Both these zeolites were synthesized with similar Si/Al ratio and characterized by various techniques such as XRD, SEM, ICP, N2 adsorption, Ammonia TPD and solid-state MAS-NMR. Olefin conversion activity over UZM-8 was found to be significantly higher than that of MCM-22. In addition to this, deactivation of UZM-8 was slower than the MCM-22. UZM-8 with irregular stacking of MWW layers possess high external surface area and exposes more number of active sites to the reactant molecules. Mesopores generated due to the disordered layers of UZM-8 allows the fast diffusion of the substrate molecules in which pore clogging does not occur, thus making it more active and slow deactivation than that of MCM-22. Graphic abstract

Cerium incorporated MCM-22 (Ce-MCM-22) was successfully synthesized by hydrothermal method. Incorporation of Ce is achieved by the optimization of method for synthesis by varying (i) Concentration of sructure directing agent or template, (ii) Silica to ceria ratio and (iii) Crystallization time. Change in phases during crystallization, variation of physico-chemical properties with respect to gel composition and framework substitution of cerium are evidenced by XRD, UV–Vis DRS, SEM, N2 adsorption, FT-IR, Ammonia TPD and solid-state MAS-NMR characterisations. It is found that incorporation of Ce into the zeolite frame work has successfully occurred by simple method of optimisimg molar gel composition. Interestingly, prepared samples of Ce-MCM-22 have also been found to be more effective catalysts for the removal of trace olefins from aromatic streams.

Silicate anion forms four, five and six coordinate complexes with chiral polyhydroxy alcohol and polyhydroxy acids in aqueous alkali media. The chemistry of organosilicate complexes is well established but its effect on zeolite synthesis has not been explored. When chiral acid is used as a template in ZSM-5 synthesis, a new partially crystalline layered silicate is formed whose basal spacing value do not match with any of the known layered silicates. Chiral acids are necessary to induce layered silicate formation and it is not formed in absence of any template or tetrapropylammonium bromide (TPABr) as a template. In presence of chiral acid, layered silicates are not precursors to ZSM-5 formation as observed normally in ZSM-5 synthesis. This method is new and it paves the way for generating layered silicates using simple chiral acids as a template.