Direct hydrogenation of CO2 to high-valued fuels is a process that can be likened to the “Trapping two fishes with a single worm”. This win–win situation addresses the ever-increasing problems associated with excessive CO2 emission as well as renewable energy supply. In this contribution, a thorough study is realized on 10 MR zeolites with one-dimensional (1D) and three-dimensional (3D) structures for the direct hydrogenation of CO2 to gasoline (C5–C11), with a high fraction of multibranched isoparaffins. Emphasis is placed on identifying the factors that favor isomerization and increase the number of branches on the isomers. Zeolites SAPO-11 and ZSM-5 were configured with Na/Fe3O4 (NaFe) in single-, dual-, and various triple-bed arrangements for this investigation. A dual-bed reaction with SAPO-11 and ZSM-5 coupled individually with the NaFe catalyst showed relatively higher selectivity for low-branched isoparaffins and aromatics, respectively. In the event of combining both the zeolites with NaFe as a physical mix and triple-bed systems, isoparaffins selectivity increased with improved multibranched isomers and reduced aromatics at the same time. Among these different tactics, the triple-bed system comprising the NaFe catalyst followed sequentially with SAPO-11 and ZSM-5 maximizes the selectivity for isoparaffins with the enhanced formation of multibranched isomers. The selectivity of gasoline reached 71.7% in hydrocarbons (HCs) with a maximum of 38.2% isoparaffins possessing a RON value of 91.7 at CO2 conversion of 31.2%. Multibranched isomers accounted for 28.3% in all C5+ isoparaffins, much higher than that of the single zeolite. Purposefully, hypothetical knowledge obtained from the prior model reactions on the zeolites served as a strong foundation to support and give insight into the results from the CO2 hydrogenation reactions.

A highly efficient one‐pot synthesis of polysubstituted pyridine has been achieved through copper‐catalyzed oxidative sp3 C−H coupling of acetophenones with toluene derivatives. Besides, the polysubstituted benzene was obtained through copper‐catalyzed coupling of acetophenones. Both of the reactions exhibited a good functional group tolerance to produce a 2,4,6‐triphenylpyridine or 1,3,5‐triarylbenzene in high yields. Compared with previous methods, these transformations allow a highly flexible and efficient preparation of substituted pyridines and benzenes.magnified image

Keen interest is taken in zeolite-encapsulated metal nanoparticles (NPs) owing to their excellent performance and ultrastability in heterogeneous catalysis. Herein, we propose a simple and efficient method to contain Fe NPs within zeolite Y microcrystals. First, a lowpressure technique was developed to successfully synthesize the zeolite Y microcrystals. The technique was then invoked, using Fe NPs fixed in nanosized C spheres as a precursor, to prepare zeolite Y-embedded Fe composite catalysts. The C spheres served as a template that restricted Fe NP growth within zeolite Y. Above all, the successful confinement of small Fe NPs within the microcrystals of zeolite Y enhanced the catalyst activity with 36.2% selectivity for light olefins (C 2 −C 4 = ) at a CO conversion of 91.2% during evaluation in Fischer−Tropsch synthesis. The techniques presented in this work open up a new avenue worth exploiting for the synthesis of nano/microcrystalline materials and highly active metal− zeolite composites in heterogeneous catalysis.

An efficient and concise approach for the synthesis of polysubstituted pyridines has been achieved through copper-catalyzed oxidative sp C-H coupling of oxime acetates with toluene derivatives. Besides, benzylamine and p-toluenesulfonylhydrazone were also introduced to react with oxime acetates to enrich the diversity of this synthetic method. These transformations provide highly flexible and facile preparation of substituted pyridines and thus are useful in practical synthesis.