Environmental-Friendly Catalytic Oxidation Processes Based on Hierarchical Titanium Silicate Zeolites at SINOPEC

Abstract

Since it was claimed by EniChem in 1983 for the first time, titanium silicate-1 (TS-1) zeolite presented the most delightful catalytic performance in the area of selective organic oxidation reactions. To enhance the mass diffusion property, hierarchical titanium silicate with hollow cavities within crystal was prepared by using a post-synthesis treatment in the presence of organic template, and then, it was commercially produced and employed in many industrial catalytic oxidation processes, such as propylene epoxidation, phenol hydroxylation, and cyclohexanone ammoximation. Moreover, we also developed several totally novel oxidation reactions on hollow titanium silicate (HTS) zeolite, i.e., Baeyer-Villiger oxidation of cyclohexanone and chlorohydrination of allyl chloride with HCl and H 2 O 2. In all cases, HTS shows much better catalytic performance than TS-1, attributing to the mass diffusion intensification by introducing hollow cavities. On the other hand, enormous works on synthesizing hierarchical TS-1 zeolites with open intracrystalline mesopores have been done via silanization treatment and recrystallization. Based on them, several bulk molecule oxidation processes with tert-butyl hydroperoxide, such as epoxidation of fatty acid methyl ester (FAME) and large olefins, have been carried out. As a consequence, hierarchical TS-1 zeolites supply a platform for developing environmental-friendly catalytic oxidation processes to remarkably overcome the drawbacks of traditional routes.

Catalytic wet peroxide oxidation of vanillic acid as a lignin model compound towards the renewable production of dicarboxylic acids

“…The higher reactivity of the catalysed reaction was due to the improvement in the H 2 O 2 nucleophilic attack capability. This effect is achieved when H 2 O 2 is adsorbed on catalyst's tetrahedral Ti active sites, forming Ti-OOH species and increasing the partial negative charges of the oxygen atoms (Xia et al, 2017). The microporosity and the hydrophobic nature of the pores are also important factors, enhancing Ti-OOH formation, avoiding solvation of Ti atoms and active species (Clerici, 2015).…”

Highly efficient catalytic production of oximes from ketones using in situ–generated H 2 O 2

“…S26 and table S7) indicated a minor shift in Ti speciation over sequential reuse in the ammoximation reaction, indicative of the formation of TiO 2 -like surface species, although no loss in catalyst activity was observed. In recent years hollow titanium silicates (HTS-1) have been developed through the postsynthesis treatment of TS-1 (32), with these materials found to offer far greater stability when used in the ammoximation reaction than the parent material (33). As such, we consider that upon potential industrial application, any deactivation of the TS-1 component can be readily overcome through the adoption of HTS-1 or alternative titanosilicate support.…”

Added-Value Chemicals from Lignin Oxidation

“…The H 2 O 2 is adsorbed in the Ti tetrahedral sites to form Ti-OOH groups that act as the active species, increasing the overall reactivity. Currently, it is used for cyclohexanone ammoximation to caprolactam and the production of propylene oxide [ 95 , 96 , 97 ]. Guaiacol peroxide oxidation using TS-1 in mild alkaline conditions achieved high percentages of MA and oxalic acid, with small percentages of FA and MAL [ 98 ].…”