Pengjing Chen

Foam-Structured NiO-MgO-Al2O3 Nanocomposites Derived from NiMgAl Layered Double Hydroxides In Situ Grown onto Nickel Foam: A Promising Catalyst for High-Throughput Catalytic Oxymethane Reforming

Catalytic oxymethane reforming is an effective and efficient route to produce syngas, but the commonly used Ni catalysts suffer from coke deposition, Ni sintering, and heat‐transfer limitations. A Ni‐foam‐structured NiO‐MgO‐Al2O3 nanocomposite catalyst was developed by thermal decomposition of NiMgAl layered double hydroxides (LDHs) in situ hydrothermally grown onto the Ni‐foam. Originating from the lattice orientation effect and topotactic decomposition of the LDH precursor, NiO, MgO, and Al2O3 are highly distributed in the nanocomposite, and thus, this catalyst shows enhanced resistance to coke and sintering. At 700 °C and a gas hourly space velocity of 100 L g−1 h−1, 86.5 % methane conversion and selectivities of 91.8/88.0 % to H2/CO are achieved with stability for at least 200 h. We believe this type of tailoring strategy and the as‐obtained materials can open up new opportunities for future applications in other high‐throughput and high‐temperature reactions.

A self-supported SS-fiber@meso-HZSM-5 core–shell catalyst via caramel-assistant synthesis toward prolonged lifetime for the methanol-to-propylene reaction

A self-supported SS-fiber@meso-HZSM-5 core–shell catalyst was essentially designed and engineered from micro- to macro-scale by caramel-assistant hydrothermal synthesis. The significant role of caramel during the crystallization process was revealed in detail. Caramel not only created the mesoporosity in the ZSM-5 crystals, but also released acid under hydrothermal synthesis conditions which lowered the zeolite crystallinity. By taking advantage of the mesopore development in a hierarchical micro–meso–macropore structure with favourably-tuned acidic properties, such a catalyst provided a dramatically prolonged lifetime of 845 h (>90% conv.) with high propylene selectivity (e.g., 48%) in the MTP reaction. The hierarchical pore structure development mainly increased the accommodation capacity of the zeolite shell for receiving formed coke thereby leading to a dramatically prolonged lifetime in the MTP reaction.

Cu-fiber-structured La2O3–PdAu(alloy)–Cu nanocomposite catalyst for gas-phase dimethyl oxalate hydrogenation to ethylene glycol

Structured Pd–Au–CuOx/Cu-fiber obtainable by a galvanic co-deposition method is post-modified by La2O3 and consequently shows promising low-temperature activity and stability for the titled reaction, due to the in situ formation of a La2O3–PdAu(alloy)–Cu nanocomposite in the reaction thereby leading to enhanced ability for H2 activation and H-spillover associated with the La2O3-assisted activation of CO and C–O groups of dimethyl oxalate.

Reaction‐Induced Self‐Assembly of CoO@Cu2O Nanocomposites In‐Situ onto SiC‐Foam for Gas‐Phase Oxidation of Bioethanol to Acetaldehyde

A high-performance SiC-foam-structured nanocomposite catalyst of CoO@Cu2 O (i.e., 50-100 nm CoO partially covered with ca. 10 nm Cu2 O) was engineered from nano- to macro-scales in one step for the high-throughput gas-phase aerobic oxidation of bioethanol to acetaldehyde. This special CoO@Cu2 O nanostructure shows much higher activity/selectivity than other binary metal-oxide assemblies such as CuOx &CoO nano-mixtures or inverse Cu2 O@CoO nanostructures. The catalyst was facilely but exclusively obtainable by in situ reaction-induced transformation of the respective metal nitrates supported on SiC-foam into the CoO@Cu2 O nanostructure in the reaction stream. It achieved 95 % conversion with 98 % selectivity under mild conditions and was stable for at least 150 h for a feed of 20 vol % ethanol (much higher than in the literature: 1-6 vol %) at a high EtOH weight hourly space velocity of 8.5 h-1 . Abundant Cu2 O-CoO interfaces and high stability of the CoO@Cu2 O nanostructure were responsible for the high activity/selectivity and promising stability in this reaction.

High sintering-/coke-resistance Ni@SiO2/Al2O3/FeCrAl-fiber catalyst for dry reforming of methane: one-step, macro-to-nano organization via cross-linking molecules

A thin-felt, microfibrous-structured Ni@SiO2/Al2O3/FeCrAl-fiber catalyst was fabricated by one-step, top-down macro–micro–nano organization with the aid of cross-linking molecules followed by a calcination treatment. This catalyst is active, selective and stable for the strongly endothermic dry reforming of methane (DRM), as the result of its enhanced resistance to coke and Ni sintering arising from its core–shell-like nanostructure. Notably, no sign of catalyst deactivation is observed, with almost no carbon deposition even after 500 h testing at 800 °C and a gas hourly space velocity of 5000 mL g−1 h−1.

Vapor-phase transport synthesis of microfibrous-structured SS-fiber@ZSM-5 catalyst with improved selectivity and stability for methanol-to-propylene

A microstructured SS-fiber@ZSM-5 core–shell catalyst engineered from micro- to macro-scale in one step is developed through a cost-effective and high-efficiency vapor-phase transport (VPT) synthesis. A sinter-locked three-dimensional microfibrous-structure consisting of 15 vol% stainless steel fibers (SS-fiber, 20 μm dia.) was dip-coated with a synthesis gel containing silicalite-1 and subsequently steamed at 180 °C using ethylenediamine (EDA) solution. The as-synthesized ZSM-5 shell contains fine coffin-shaped crystals and small grains with remarkable intercrystalline mesopores derived from the initial aggregated aluminosilicate particles while the mesopore size is ever-changing with the progression of the crystallization. The catalyst lifetime for the MTP reaction shows a volcano-like evolution against the VPT time length, which correlates well with the crystallization-time-dependent amount of Bronsted acid and mesoporosity. The most promising SS-fiber@HZSM-5 catalyst is the one obtained via VPT synthesis for 120 h, with a high shell diffusion coefficient of 1.6 × 10−14 m2 s−1, delivering a prolonged single-run lifetime of 45 h with a high propylene selectivity of ∼46.9% at 450 °C at a high methanol weight hourly space velocity (WHSV) of 10 h−1.