Metal clusters encapsulated in zeolites have attracted increasing attention because of their unique electronic properties with high stability, but diffusion limitation is the bottleneck in the utilization efficiency of active sites, especially in bulk crystals. Nanosized zeolites could effectively improve mass transport by shortening the diffusion length. However, their rough surface and low crystallinity lead to a high surface barrier and low stabilization effect, respectively. Here, we developed a dualtemplate method to synthesize finned MFI zeolites to encapsulate PtZn clusters. In a propane dehydrogenation reaction, the as-prepared PtZn@S-1-Fin exhibited a high specific activity of 17.0 mol C3H6 mol Pt −1 s −1 at 600 °C, which was about 1.7 times higher than that of PtZn confined in a nanosized zeolite. This could be attributed to the epitaxial highly crystallized zeolite combining a short diffusion length and a high surface permeability simultaneously.

Polydopamine-coated MWCNTs have been employed as reactive platforms for the anchoring of multiple heteroatom dopants.

Hydrocracking of long-chain paraffins is a key process in petroleum refining. A fundamental understanding of the reaction on the bifunctional catalyst is of great importance for controllable cracking. In this work, a mechanism study on the hydrocracking of long-chain paraffins catalyzed by Pt/ZSM-23 has been carried out. The distribution and accessibility of acid sites on MTT channels are purposefully adjusted. Based on reasonable simplification, the reaction data are analyzed to reveal the shape selectivity, reaction path, and catalytic mechanism. The applicability of the pore-mouth mechanism in this system has been carefully verified by experiments. Both protonated cyclopropane (PCP) and β-scission paths occurred simultaneously at the pore mouths, accounting for 60 and 40%, respectively. The proportions of PCP and β-scission paths with different chain lengths inserted in the pore are quantitatively calculated, which are multimodal. Shape selectivity of the teardrop-shaped MTT skeletal structure is investigated by the joint experimental−theoretical method. The insertion of the paraffin chain in the MTT channel is discretely segmented by integral multiples of four sequential carbon atoms starting at one end of the chain, which is followed by cracking through the mixed PCP and β-scission paths at pore mouths.

The simultaneous enhancement of activity and selectivity during hydrogenation is a great challenge. Herein, by encapsulating Pt nanoparticles (NPs) into the hierarchical defective metal−organic framework (MOF) of UiO-66, the steric screening effect of the pores, Lewis acid sites of the nodes, and metal-MOF synergy have been finely tuned and effectively utilized for selective hydrogenation. Benefiting from optimal meso/micropores, favorable Lewis acid sites and strengthened metal−support interaction, Pt NPs encapsulated in hierarchical UiO-66 exhibited superior performance in selective hydrogenation. With the proper loading of Pt NPs into suitable meso/microporous UiO-66, the conversion of cinnamaldehyde is increased from 18.2% to 85% along with the selectivity for cinnamyl alcohol being improved from 15.8% to 76% under 70 °C and 2 MPa. The conventional trade-off relationship between increasing selectivity and promoting activity for encapsulated metal catalysts has been broken with the as-developed catalyst. This study provides a promising strategy to optimize transformation efficiency by the design of a tailored MOF-based framework for encapsulating metal NPs with the needed steric effect and synergistic effect.

Hydrodesulfurization (HDS) is an important technique that is widely adopted in the petroleum industry to remove harmful sulfur compounds for environmental protection. MoS2 is the most commonly employed HDS catalyst but tends to stack due to its high surface energy. Active MoS2 nanosheets are anticipated to be well supported for preventing aggregation and increasing accessibility. In the current study, two-dimensional Ti3C2 MXene is utilized as a novel support to controllably anchor MoS2 nanosheets for efficient HDS. The composite of Ti3C2-supported CoMoS2 (CoMoS2/Ti3C2) with a 3D interconnected network was successfully constructed by a facile, one-step hydrothermal method. Detailed characterizations showed that MoS2 nanosheets vertically grew in situ on and between the layers of Ti3C2 MXene. CoMoS2/Ti3C2 possesses a well-defined open structure with a larger specific surface area and a higher proportion of CoMoS active phase compared with unsupported CoMoS2. As catalyzed by CoMoS2/Ti3C2, the reaction rate constant was effectively increased to 2.8 times that on CoMoS2 for the HDS of dibenzothiophene. CoMoS2/Ti3C2 also showed good stability in a harsh high-temperature reaction environment.

Tetracyclo[6,2,1,01,7,13,6]dodecene (TCD) is conventionally synthesized by continuous heating of norbornene (NBE) and dicyclopentadiene (DCPD), in which the synthesis rate and isomer selectivity are hardly improved under such near equilibrium conditions. In this study, an alternative thermochemical synthesis technique using direct electric heating is present. Alternate heating and cooling of the reaction mixture can be rapidly realized by programmable electric current flowing in the reactor tube. The reaction has been switched in a timely fashion between high temperature and low temperature at a given speed. At a high temperature, the active intermediate of cyclopentadiene (CPD) quickly forms. Rapid cooling ensures the nonequilibrium kinetic control of CPD copolymerization for increasing the selectivity. The energy cost is reduced by lowering the average temperature. As optimized by the Bayesian method, the operating conditions of oscillating heating (e.g., amplitude, frequency, pressure, and so on) are determined to precisely match the time scales of fast generation and directed consumption of CPD. The oscillating heating method leads to a high yield of endo,exo-TCD (62.4% versus 11.6% by the conventional continuous-heating method). High-energy-density fuels with good low-temperature fluidity are prepared using hydrogenated TCD as the key component.

Steam methane reforming (SMR) is the most mature technology for hydrogen production in industry, and alumina supported nickel (Ni/Al 2 O 3 ) is the most widely used catalyst. Herein, the key role of Ni valence state on the catalytic SMR performance of Ni/Al 2 O 3 is reported. The ratio of Ni 0 /Ni 2 + on Ni/ Al 2 O 3 is individually and effectively tuned by changing the reduction temperature after wet impregnation. Catalytic performance of Ni/Al 2 O 3 is greatly dependent on the surface concentration of Ni 0 and Ni 2 + . The catalyst reduced at 675 °C possesses balanced Ni 0 and Ni 2 + sites and exhibits superior catalytic performance, on which 60 % of methane is stably converted at 600 °C. CH 4 -TPD and CO-TPD profiles demonstrate that appropriate Ni 0 /Ni 2 + ratio can promote the adsorption of CH 4 and inhibit the moderate-strength adsorption of CO, which leads to increased SMR activity and selectivity.

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