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[Display omitted] • Dynamic hydrothermal method could accelerate the Ni-phyllosilicate synthesis. • Glycerol modification significantly reduced the thickness of Ni-phyllosilicate nanosheets. • Synergistic effect of stirring and viscous solvent led to enhanced activity for CO 2 methanation. • Viscous solvent-assisted dynamic hydrothermal method was competitive to synthesize Ni-phyllosilicate. To address the shortcomings of poor convection and product agglomeration of the static hydrothermal method, the dynamic hydrothermal method together with the viscous solvent-assisted dynamic hydrothermal method were proposed to synthesize Ni-phyllosilicate in this work. Stirring seemed to be powerful to accelerate the synthesis with significant increase of Ni content from 11.80 wt% (static synthesis) to 23.13 wt% (dynamic synthesis). The further modification of glycerol increased the shearing force to exfoliate the Ni-phyllosilicate nanosheets during dynamic synthesis, whose thickness could reach 1.17 nm with improved metal utilization ratio after reduction. As a result, the activity of CO 2 methanation was enhanced with large TOF CO2 of 3.5 × 10−2 s−1 and small E a of 65.13 kJ·mol−1. In situ DRIFTS analysis confirmed the existence of high actively intermediate of m -HCOO− and *CO, which could be further hydrogenated into CH x species. In short, the synergistic effect of dynamic stirring and glycerol modification drove the enhancement of catalytic activity, and also provided the possibility of large-scale production of Ni-phyllosilicate using hydrothermal method. [ABSTRACT FROM AUTHOR]

This work reported an efficient one-pot hydrothermal method for adding promoter to nickel phyllosilicate. The nickel‑samarium bimetallic phyllosilicate (NiSm-Ps) was formed during the one-pot synthesis. The characterization results showed that the Sm species over the uncalcined NiSm-Ps catalyst existed in the form of Sm 2 Si 2 O 7 , and it was converted to be Sm 2 O 3 after calcination with high dispersion, and in the form of Sm 2 O x after reduction. On the contrary, for the post-impregnated Sm-doped nickel phyllosilicate catalyst (Ni-Ps/Sm-Im), the Sm species variation was from Sm 2 O 3 to Sm 2 O x , which was significantly different from that of NiSm-Ps. As a result, the NiSm-Ps catalyst showed a high Ni dispersion (13.9%), small particle size (4.0 nm) and large concentration of surface oxygen vacancies as well as strong H 2 and CO 2 activation properties. Consequently, the NiSm-Ps catalyst achieved a high CO 2 conversion of 80.1% at 400 °C and large TOF CO2 of 4.08 × 10−3 at 220 °C. Additionally, NiSm-Ps exhibited excellent long-term stability and anti-sintering property. In short, the formation of Sm 2 Si 2 O 7 was very crucial for the Ni-Sm/SiO 2 catalyst and could further improve the promotion effect of Sm species for CO 2 methanation. [Display omitted] • The Ni Sm bimetallic phyllosilicate catalyst was synthesized by a one-pot strategy. • Sm 2 Si 2 O 7 was the important intermediate product of the one-pot synthesized catalyst. • Sm 2 O 3 rather than Sm 2 Si 2 O 7 was observed on the post-impregnated catalyst. • The occurrence of Sm 2 Si 2 O 7 led to the more significant promotion effect for CO 2 methanation. [ABSTRACT FROM AUTHOR]

Addressing the problems of easy collapse, Ni sintering and low catalytic activity over the nanotubular nickel phyllosilicate catalyst, the Mg species was doped via a simple hydrothermal method to construct the nanotubular Ni-Mg bimetallic phyllosilicate solid solution. The high thermal stability, nonreducible property and strong basicity of magnesium species led to the enhancement of anti-collapse, Ni-sintering resistance and basicity. As a result, the fine Ni particles and enhanced H 2 and CO 2 chemisorption and activation properties resulted in boosting the catalytic activity of both CO 2 methanation and CH 4 -CO 2 reforming reactions. The Ni/Mg ratios and the reduction temperatures were detailed optimized, and the 600oC-reduced Ni 8 Mg 2 -NT catalyst with the Ni/Mg ratio of 8:2 was the optimal, which also exhibited high long-term stability. In short, the formed Ni-Mg-phyllosilicate solid solution structure and the special interactions of different species brought about high catalytic performance of the nanotubular Ni-Mg phyllosilicate catalyst. [Display omitted] • The nanotubular Ni-Mg bimetallic phyllosilicate solid solution was synthesized. • Nanotubular Ni-Mg phyllosilicate obtained high anti-collapse and Ni-sintering resistance properties. • The Ni/Mg ratio of 8:2 and the reduction temperature of 600 oC were the optimum. • This catalyst was versatile for both CO 2 methanation and CH 4 -CO 2 reforming reactions. [ABSTRACT FROM AUTHOR]

• Catalytic mechanism of hydrogen bonds on –CHO during DCL was firstly proposed. • Generation mechanism of –CHO was studied with experimental and theoretical ways. • Hydrogen bonds obviously affect hydrogen transfer and liquefaction reactivity. • Hydrogen bonds modulation is proposed during selection of liquefaction solvents. Direct coal liquefaction (DCL) is considered to be the effective method for production of aviation fuel and valuable chemicals, while low rank coal is appropriate feedstock because of high thermal reactivity. Original hydrogen bonds could promote low-temperature crosslinking reactions. liquefaction solvents could partially break original hydrogen bonds by forming new species. Impacts of hydrogen bonds formed by solvents on DCL reactions have rarely been studied. In order to figure out role of hydrogen bonds in DCL, a conjoint study of DCL experiments and density functional theory (DFT) calculations was carried out. More carboxyl groups were promoted to decompose. Meanwhile more aldehyde groups were found in solid products with increase of liquefaction temperature. As aldehyde groups are generated, hydrogen consumption increases. In terms of mechanism, effect of stronger hydrogen bonds on cleavage of covalent bonds were investigated by DFT-based potential energy surface scan. It turns out that cleavage of C O bonds in carboxyl groups could be enhanced, so that stabilization of free radicals results in consumption of extra hydrogen, which is provided by tetralin. Results of experimental methods are consistent with DFT calculations. The catalytic mechanism of hydrogen bonds upon conversion of carboxyl groups during DCL is proposed. Hydrogen bonds between coal and liquefaction solvents promote decomposition of carboxyl groups and consequently improve hydrogen transfer and thermal reactivity of solid products. Consequently, hydrogen bonds modulation should be taken into account during preparation of DCL solvents, for suppression of crosslinking reactions. [ABSTRACT FROM AUTHOR]

In this work, a series of Pt–Ce 0.63 Zr 0·37 O 2 –Y catalysts were prepared by unique simple mechanical mixing method. The catalytic activity of these catalysts for toluene oxidation was investigated. The physicochemical properties of the catalysts were characterized by XRD, ICP-MS, SEM, TEM, XPS and N 2 sorption. Pore size distribution was analyzed according nitrogen adsorption and desorption isotherms. The catalytic results showed that using NaY as support for Pt–Ce 0.63 Zr 0·37 O 2 –Y could enhance the conversion of toluene during the oxidation process in comparison with HY. Further mixing cerium zirconium solid solution with Pt–NaY can improve the oxidation catalytic property of these catalysts. The conversion of toluene over Pt–Ce 0.63 Zr 0·37 O 2 –NaY reached more than 90% at 200 °C. High catalytic stability was obtained for toluene oxidation over Pt–Ce 0.63 Zr 0·37 O 2 –NaY. Platinum, cerium and zirconium can be uniformly dispersed on Y zeolite with small particle size by simple mechanical synthesis. The effect of drying methods on catalytic activity and hydrothermal stability of catalysts were also investigated in this research. [Display omitted] • Pt–Ce 0.63 Zr 0·37 O 2 –Y was synthesized by a unique simple mechanical mixing method. • High catalytic activity of Pt–Ce 0.63 Zr 0·37 O 2 –NaY was shown for toluene oxidation. • The hydrothermal stability of Pt–Ce 0.63 Zr 0·37 O 2 –Y was investigated. • Drying methods had no effect on the catalytic activity of the catalysts. • The addition of Pt and CeZrO can improve the oxidation performance of catalyst. [ABSTRACT FROM AUTHOR]