Menghui Yan,Fang Jin,Yigang Ding,Guiying Wu,Rong Chen,Luhui Wang,Yuanzhi Yan
A novel titanosilicate zeolite was synthesized by a sequential treatment of ERB-1 with deboronation and atom-planting method to develop an epoxide catalyst. The Fourier transform infrared (FTIR) and the diffuse reflectance infrared Fourier transform (DRIFT) characteristic results reveal that the silanol hydroxyl nests generated by deboronation process are further consumed by the dehydrochlorination of TiCl4 during the atom-planting treatment. At the same time, the titanium species are incorporated into the framework of MWW structure. The energy-dispersive spectroscopy (EDS), ultraviolet-visible light (UV-vis), and ultraviolet resonance Raman spectroscopy (UVRRS) characterization results reveal that the amount and coordination states of the incorporated Ti species can be controlled by the atom-planting treatment time and temperature. The catalytic performance of the new titanosilicates in the epoxidation of 1-hexene with H2O2 and of cyclohexene with tert-butyl hydroperoxide is compared for the efficiency of Ti species in the hydrophilic and hydrophobic system. The catalytic results show the framework tetrahedral coordinated titanium species are more efficient for epoxidation than extra-framework octahedral Ti species.
Liquid-phase hydrodeoxygenation (HDO), catalyzed by metal or metal-acid sites, provides an effective catalytic strategy to remove oxygen-containing functionalities of lignin-derived phenolic compounds on the route to fuels and chemicals. Developing the catalyst with high activity and stability is crucial for such a chemical process but still remains a significant challenge. In this contribution, highly dispersed subnanometric Ru metal clusters (<1.5 nm) encapsulated in the cavities of MWW zeolites, including HMCM-22 and its siliceous analog ITQ-1, have been developed for the HDO of guaiacol, an important lignin-derived phenolic monomer, in an apolar liquid phase under mild conditions (160 °C, 3 MPa H2). We validate the effective encapsulation of Ru metal clusters in ITQ-1 and HMCM-22 zeolite cavities via complementary characterization methods. The detailed reaction pathways of the HDO of guaiacol are depicted by using guaiacol, phenol, and anisole as reactants. The subnanometric Ru metal clusters confined in MWW zeolite thin layers (20–30 nm in thickness) show remarkable enhancement in HDO activity compared to the large metal particles. The close proximity between Ru metal clusters and Brønsted acid sites (BAS) confined in zeolite constraints delivers a synergistic effect, leading to an additional enhancement in catalytic activity as well as product selectivity. The super stability of the ultrafine Ru metal clusters against sintering and leaching after successive catalytic runs is achieved. The well-defined mono- or bifunctional Ru-containing MWW zeolite catalysts enable the fundamental understanding of HDO of lignin-derived phenolic compounds in the apolar liquid phase and also provide a prototype for the design of superior catalysts for other energy-related transformations.
危险品化学品经营许可证（带存储）