Yakun Li

Structured Ni‐CeO2‐Al2O3/Ni‐Foam Catalyst with Enhanced Heat Transfer for Substitute Natural Gas Production by Syngas Methanation

Concerns about the clean utilization of coal and the development of sustainable energy have provided a particular impetus for the exploration into the production of substitute natural gas (SNG) by syngas methanation in some parts of world. Owing to heat‐transfer limitations, current SNG technology based on a series of fixed‐bed reactors packed with oxide‐supported Ni catalysts suffers from issues such as high costs, low efficiency, and catalyst sintering. We report a monolithic Ni‐Ce‐Al2O3/Ni‐foam catalyst obtainable by modified wet‐chemical etching of Ni foam. Such a catalyst, with significantly enhanced heat transfer, is highly active, highly selective, and very stable for syngas methanation. Computational fluid dynamics calculations and experimental measurements consistently show a large reduction in the “hotspot” temperature in the Ni‐foam‐structured catalyst bed owing to high thermal conductivity. We anticipate that our approach will open a new opportunity for next‐generation SNG plant design.

Endogenous growth of 2D AlOOH nanosheets on a 3D Al-fiber network via steam-only oxidation in application for forming structured catalysts

We report a facile, green and generalized method of endogenous growth of 2D boehmite nanosheets (ns) on a 3D network using Al-fibers through oxidation reaction between the Al metal and H2O (2Al + 4H2O = 2AlOOH + 3H2). Such Al-fiber@ns-AlOOH composites have substantial potential applications for microfibrous-structured catalysts and catalytic reactors, being verified by several hot-topic reactions such as CO oxidative coupling to dimethyl oxalate.

Structured nanoporous-gold/Al-fiber: galvanic deposition preparation and reactivity for the oxidative coupling of methanol to methyl formate

Microfibrous-structured nanoporous gold (NPG) on Al-fiber catalysts, obtained by galvanic deposition onto a 3D network using 50 μm Al-fiber, is cost-effective (low Au-loading, e.g., 1 wt%), highly active/selective (>90% selectivity at >50% conversion) and stable (at least 300 h without NPG sintering) for oxidative coupling of methanol to methyl formate.

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.

Catalytic distillation for ethyl acetate synthesis using microfibrous-structured Nafion–SiO2/SS-fiber solid acid packings

Catalytic distillation (CD) offers a unique integration of distillation and catalysis to selectively separate products in situ while making a positive shift of chemical equilibrium and has therefore been well received as an inviting avenue to green chemical processing. Rendering novel structured catalytic packings is particularly desirable but remains challenging. Herein, we present a microfibrous-structured Nafion–SiO2/SS-fiber solid acid catalyst and demonstrate its separation and reaction efficiency as CD packings for esterification to produce ethyl acetate from acetic acid and ethanol. A thin-sheet microfibrous structure with 15 vol% 20 μm stainless steel fibers (SS-fiber) and 85 vol% void volume was shaped into θ-ring analogues. Nafion was then firmly locked into the SiO2 layer that was anchored onto the SS-fiber surface by a dip-coating method using self-crosslinking Nafion–SiO2 sol–gel prepared by Nafion-catalyzed hydrolysis of tetraethylorthosilicate (TEOS). Such micro-structured Nafion catalysts worked effectively and efficiently in the CD for esterification of acetic acid with ethanol as the result of a unique combination of high catalyst performance (stability, adequate acidic sites and high mass/heat transfer) and instantaneous distillation. For instance, high total (93.6%) and actual (91.6%) yields of ethyl acetate with 96.2% purity were achievable at a high space-time yield (4.3 g mmol−1 h−1) while the high CD efficiency was maintained for 40 h over 5 consecutive batch runs.