Chaoqun Bian

Solvent-free synthesis of zeolites from anhydrous starting raw solids.

Development of sustainable routes for synthesis of zeolites is very important because of wide applications of zeolites at large scale in the fields of catalysis, adsorption, and separation. Here we report a novel and generalized route for synthesis of zeolites in the presence of NH4F from grinding the anhydrous starting solid materials and heating at 140-240 °C. Accordingly, zeolites of MFI, BEA*, EUO, and TON structures have been successfully synthesized. The presence of F(-) drives the crystallization of these zeolites from amorphous phase. Compared with conventional hydrothermal synthesis, the synthesis in this work not only simplifies the synthesis process but also significantly enhances the zeolite yields. These features should be potentially of great importance for industrial production of zeolites at large scale in the future.

Solvent‐Free Syntheses of Hierarchically Porous Aluminophosphate‐Based Zeolites with AEL and AFI Structures

Development of sustainable routes for synthesizing aluminophosphate-based zeolites are very important because of their wide applications. As a typical sustainable route, solvent-free synthesis of zeolites not only decreases polluted wastes but also increases product yields. Systematic solvent-free syntheses of hierarchically porous aluminophosphate-based zeolites with AEL and AFI structures is presented. XRD patterns and SEM images show that these samples have high crystallinity. N2 sorption isotherm tests show that these samples are hierarchically porous, and their surface areas are comparable with those of corresponding zeolites from hydrothermal route. Chosen as an example, catalytic oxidation of ethylbenzene with O2 shows that cobalt substituted APO-11 from the solvent-free route (S-CoAPO-11) is more active than conventional CoAPO-11 from hydrothermal route owing to the sample hierarchical porosity.

Aluminium-rich Beta zeolite-supported platinum nanoparticles for the low-temperature catalytic removal of toluene

The removal of volatile organic compounds is an important aspect of sustainability and environmental protection. Catalytic oxidation is one of the most efficient routes to achieve this. The K+ form of an aluminium-rich Beta zeolite-supported Pt nanoparticle (2.2 nm) [Pt/KBeta-seed-directed synthesis (SDS)] catalyst is very active for the low-temperature catalytic removal of toluene and results in full conversion at a much lower temperature than a conventional KBeta-supported Pt nanoparticle (Pt/KBeta-TEA) catalyst. The higher activity of the Pt/KBeta-SDS catalyst compared with the Pt/KBeta-TEA catalyst is related to the advantages of the higher K+ content and fewer terminal silanol defects in the KBeta-SDS catalyst than in the KBeta-TEA catalyst. The higher K+ content is helpful for the formation of more Pt0 species, and both the higher K+ content and the lower number of terminal silanol defects are favourable for the adsorption of toluene, as evidenced by XPS and the toluene-TPD profiles. More importantly, the Pt/KBeta-SDS catalyst shows very stable activities in the presence of H2O and CO2 in the feed gases. The combination of this extraordinary activity and excellent stability in the catalytic removal of toluene over the Pt/KBeta-SDS catalyst are important for future environment protection.

Design and synthesis of an efficient nanoporous adsorbent for Hg2+ and Pb2+ ions in water

An efficient nanoporous adsorbent for Hg2+ and Pb2+ ions in water has been synthesized from the interaction of aqueous NaH2C3N3S3 and Na3C3N3S3 solutions. The Raman spectra of the sample indicate that the S–S bonds have been formed by this interaction, and N2 sorption isotherms together with TEM images indicate the presence of hierarchical nanopores (mesopores/macropores). Interestingly, this nanoporous sample exhibits excellent adsorption behavior of heavy metal ions in water, giving the adsorption capacity of Hg2+ and Pb2+ at 735.3 and 375.9 mg g−1, respectively. The Hg2+ and Pb2+ sorption isotherms are typical Langmuir and their kinetic model follows the pseudo-second-order. These results indicate that the adsorption behavior of the Hg2+ and Pb2+ ions on the sample is chemical. More importantly, this sample can be recycled 4 times without obvious loss of the adsorption ability in water, which is very important for its industrial applications in the future.

A Hierarchical Bipyridine‐Constructed Framework for Highly Efficient Carbon Dioxide Capture and Catalytic Conversion

As a C1 feedstock, CO2 has the potential to be uniquely highly economical in both a chemical and a financial sense. Porous materials bearing particular binding and active sites that can capture and convert CO2 simultaneously are promising candidates for CO2 utilization. In this work, a bipyridine-constructed polymer featuring a high surface area, a hierarchical porous structure, and excellent stability was synthesized through free-radical polymerization. After metalation, the resultant catalysts exhibited superior activities in comparison with those of their homogeneous counterparts in the cycloaddition of CO2 to epoxides. The high performance of the heterogeneous catalysts originates from cooperative effects between the CO2 -philic polymer and the embedded metal species. In addition, the catalysts showed excellent stabilities and are readily recyclable; thus, they are promising for practical utilization for the conversion of CO2 into value-added chemicals.

Solvent-free synthesis of titanosilicate zeolites

A solvent-free route is developed for synthesizing titanosilicate zeolites with good crystallinity, uniform crystals, high surface area, and tetrahedral Ti species in the framework. Catalytic tests show that S-TS-1 exhibits almost the same catalytic activity in hexane oxidation with H2O2 as that of conventional TS-1 synthesized by a hydrothermal route.

Controllable cyanation of carbon-hydrogen bonds by zeolite crystals over manganese oxide catalyst

The synthesis of organic nitriles without using toxic cyanides is in great demand but challenging to make. Here we report an environmentally benign and cost-efficient synthesis of nitriles from the direct oxidative cyanation of primary carbon-hydrogen bonds with easily available molecular oxygen and urea. The key to this success is to design and synthesize manganese oxide catalysts fixed inside zeolite crystals, forming a manganese oxide catalyst with zeolite sheath (MnOx@S-1), which exhibits high selectivity for producing nitriles by efficiently facilitating the oxidative cyanation reaction and hindering the side hydration reaction. The work delineates a sustainable strategy for synthesizing nitriles while avoiding conventional toxic cyanide, which might open a new avenue for selective transformation of carbon-hydrogen bonds.

Improved catalytic activity in methanol electro-oxidation over the nickel form of aluminum-rich beta-SDS zeolite modified electrode

A glass carbon electrode was modified by the nickel form of an aluminum-rich beta-SDS zeolite synthesized from an organotemplate-free and seed-directed route. Catalytic tests in the electro-oxidation of methanol show that this modified electrode exhibits improved catalytic activity, compared with the electrode modified conventional nickel form of beta zeolite.

Generalized high-temperature synthesis of zeolite catalysts with unpredictably high space-time yields (STYs)

As a class of important catalysts and adsorbents, zeolites are normally prepared through hydrothermal synthesis, whereby a relatively long crystallization time and use of a large amount water solvent strongly hinder the enhancement of zeolite space-time yields (STYs), which is a critical factor for the industrial manufacturing. To overcome this limitation, herein we report a novel strategy for highly efficient zeolite synthesis by means of fast crystallization at high temperatures (200–240 °C) in the absence of water solvent. This concept significantly enhances the crystallization rates and allows drastic reduction of the time required for crystallization of the zeolite frameworks such as the crystallization of MFI from 12–24 h at 180 °C to 0.5 h at 240 °C and RUB-36 from 14 days at 140 °C to 1.5 days at 200 °C. Together with much better utilization of the reactor volume, the space-time yields (STYs) for zeolites prepared from high-temperature synthesis in the absence of water solvent can be remarkably increased. The STYs of MFI and RUB-36 are as high as 11 000 and 178 kg m−3 per day, which are almost two orders of magnitude higher than those of conventional hydrothermal synthesis. This novel synthesis method should be applicable for synthesizing a wide variety of zeolite structures and bears the potential for highly efficient zeolite synthesis on an industrial scale.