Bin Qin

The development of adsorbents for ammonia capture and separation is a challenging task, with significant industrial relevance. We report herein, for the first time, open aluminophosphate frameworks for on-demand ammonia adsorption. Under ambient conditions, the AlPO-18 molecular sieve exhibits exceptional dynamic ammonia uptake of 3.36 mmol/g at an extremely low ammonia concentration of 200 ppm, showing great potential as a disposable adsorbent for trace ammonia capture. AlPO-11 molecular sieve manifests a desirable ammonia dynamic uptake of 5.73 mmol/g at high ammonia concentration of 50,000 ppm, with excellent recyclability upon regeneration under mild conditions. Aspen simulations demonstrate the advantage of the adsorptive separation process employing AlPO-11 adsorbent for ammonia recovery, with huge energy savings of 51% in comparison with the compression-based process currently employed in the ammonia synthesis industry. The underlying mechanism of ammonia adsorption and the nature of ammonia binding in aluminophosphate frameworks are fully elucidated by employing a combination of X-ray photoelectron spectroscopy, in situ Fourier transform infrared spectroscopy, quasi in situ magic angle spinning nuclear magnetic resonance, and density functional theory calculations. The coordination of ammonia on the framework aluminum sites in aluminophosphates is clearly disclosed. The development of low-cost and commercially available aluminophosphate molecular sieves may unlock their potential for on-demand ammonia capture and separation in various scenarios.

The selective oxidation of olefins by molecular oxygen holds great importance in the chemical industry due to its remarkable adaptability in constructing carbonyl compounds. Classical homogeneous Wacker oxidation with a complex system of PdCl₂-CuCl₂-H₂O is currently employed in the industrial production of acetaldehyde, which suffers from several key drawbacks. The development of alternative heterogeneous catalytic systems for Wacker-type oxidations has been hotly pursued for decades. Herein, we report a novel heterogeneous catalyst, namely Pd@FAU containing exclusive singular Pd sites confined in zeolite, showing remarkable performance in the Wacker-type oxidation of light olefins to the corresponding carbonyl compounds. Typically, stable propylene conversion rates of 2.3-3.5 mol/mol_Pd/min and an acetone selectivity of 75-89% can be achieved simultaneously, surpassing the state-of-the-art homogeneous Wacker oxidation systems. In situ spectroscopic investigations disclose the spontaneous redox cycle of Pd⁺-Pd²⁺-Pd⁺ in Pd@FAU during the reaction, in significant contrast to the known Pd²⁺-Pd⁰-Pd²⁺ redox cycle. Theoretical calculations reveal the unique reaction pathway and mechanism of Wacker-type oxidation over Pd@FAU, without the participation of water as the nucleophile. Overall, a novel heterogeneous catalyst of Pd@FAU has been developed for Wacker-type oxidations with the unique reaction mechanism fully interpreted. This study will contribute to more sustainable Wacker-type oxidations and further improve the current understanding of Pd redox catalysis.

Understanding the unique behaviors of atomically dispersed catalysts and the origin thereof is a challenging topic. Herein, we demonstrate a facile strategy to encapsulate Pt^δ+ species within Y zeolite and reveal the nature of selective hydrogenation over a [email protected] model catalyst. The unique configuration of [email protected], namely atomically dispersed Pt^δ+ stabilized by the surrounding oxygen atoms of six-membered rings shared by sodalite cages and supercages, enables the exclusive heterolytic activation of dihydrogen over Pt^δ+···O^2– units, resembling the well-known classical Lewis pairs. The charged hydrogen species, i.e., H⁺ and H^δ−, are active reagents for selective hydrogenations, and therefore, the [email protected] catalyst exhibits remarkable performance in the selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols and of nitroarenes to arylamines.

CO₂ conversion to methanol and CO is studied by DFT-based microkinetic simulations over the defective cubic In₂O₃ catalyst.

A novel hexagonal In ₂ O ₃ with high proportion of exposed {104} facets shows superior performance for CO ₂ hydrogenation to CH ₃ OH.

Dissociative adsorption of H₂ and migration of the adsorbed H adatom over cubic and hexagonal In₂O₃ catalysts were investigated.