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BACKGROUND Because of increasing environmental contaminations, hydrogen has attracted much attention as an effective and clean energy source. In addition, hydrogen and syngas are raw materials used in the production of valuable compounds. Methane dry reforming is one common method for syngas production. In this work, Ni catalysts supported on different ZnO–Al2O3 composite oxides were prepared. The effects of variation in Zn/Al ratio (Zn/Al = 0, 0.33, 0.5, 1, 2 and 3) on physico‐chemical properties and their activity and stability in methane dry reforming were investigated. RESULTS The results indicated that Zn addition led to decreasing surface area, weakening the interaction between active phase and support, improving Ni reduction and therefore enhancing initial activity. CONCLUSION When Zn content was low or just enough to produce ZnAl2O4 phase, only metallic Ni particles were detected after reaction which led to carbon filaments formation and deactivation of catalysts. Increasing Zn content formed NiZn alloy that played essential roles in activity and stability. High amounts of Zn (Zn/Al = 3) did not favor promoting effects due to the increasing active phase sizes and decreasing contact area. Ni/ZnO–Al2O3 with Zn/Al = 2 exhibited the highest activity and stability in methane dry reforming. © 2018 Society of Chemical Industry

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An effective approach for tuning CO 2 adsorption, activation and transformations of various epoxides in CO 2 fixation reactions is introducing functional groups into the pores of metal-organic frameworks (MOFs) through ligand modification. Herein, a novel ionic ligand, 1,5,7-triazabicyclo[4.4.0]dec-5-ene-biphenyl-4,4'-dicarboxylic acid (H 2 BPDCÀ [TBD] + Br À ), was synthesized to construct derivatives of the cationic guanidinium-containing Zr-MOF (UiO67-[TBD] + Br À ) with free bromide ions, as multifunctional heterogeneous catalysts. The materials were characterized comprehensively by multiple techniques such as PXRD, FTIR, TGA, SEM, EDS, 1 H NMR, 13 C NMR, mass spectrometry (MS), elemental analysis, as well as N 2 and CO 2 adsorption measurements. The synthesized UiO67-[TBD] + Br À exhibits an efficient heterogeneous catalytic performance in the CO 2 fixation reaction with epoxides, with high yield and selectivity, under mild conditions (0.1 MPa CO 2 , 80 °C, without co-catalyst and solvent). In addition, these catalysts display good thermal stability, recyclability and could be reused at least five times without a significant decrease in their catalytic performance.