Solar-Driven Synchronous Photoelectrochemical Sulfur Recovery and Pollutant Degradation

Highly efficient selective hydrogenation of nitrocyclohexane (NCH) to cyclohexanone oxime (CHO) is important for the production of caprolactam. In this work, NiTi catalysts (NiTi-IMP, NiTi-HDT, and NiTi-LDH) were prepared by different methods and applied in NCH hydrogenation to CHO. It was found that NiTi-LDH with rich oxygen vacancies (Ov) induces a strong metal−support interaction (SMSI) between Ni and TiO 2 , hence favoring the dispersion of Ni nanoparticles, promoting the reduction of NiO and the formation of much more metallic Ni, and facilitating the electron transfer between Ni and Ti. In situ DRIFTS reveals the mechanism for NCH hydrogenation on Ov-rich NiTi-LDH, showing that Ov benefits the enhancement of NCH conversion and suppresses overhydrogenation to the byproducts of cyclohexanone (CHone) and cyclohexylamine (CHA). Moreover, density functional theory (DFT) calculations illustrate that Ov facilitates the adsorption of NCH and desorption of CHO, favors the α-H transfer of nitrosocyclohexane (N−CHH) to CHO, and significantly reduces the overall reaction energy barrier of NCH to CHO. Under optimum conditions, NiTi-2 with the largest amount of Ov gives 90.71% selectivity to CHO at 99.84% NCH conversion. This study provides an efficient and economical catalyst for the preparation of CHO from NCH, and it is valuable for promoting the industrial production of caprolactam toward resource conservation and environment friendliness.

Section: Catalyst Synthesismentioning

confidence: 99%

Highly Efficient Hydrogenation of Nitrocyclohexane to Cyclohexanone Oxime over NiTi-Layered Double Hydroxide: The Key Role of Oxygen Vacancies

Zhang,

Liao,

Cui

et al. 2023

“…A selective H 2 S adsorption was achieved through N–H bonding between N in tertiary amine and H in H 2 S, as described in the following eq (eq ) Although the adsorption capacity and selectivity of H 2 S on the tertiary-amine-modified MBS on silica were improved in the presence of CO 2 , H 2 S adsorption capacity was too low to be practical for industrial applications. Studies of the role of H 2 S in life evolution were reviewed by Olson et al in 2016 in which photoelectrons stimulate CO 2 reduction to methane (CH 4 ) in the presence of H 2 S. Similar H 2 S conversion through photocatalysis is also known in the literature, − which inspires us that CO 2 may show a positive effect on H 2 S adsorption over carbon-based materials.…”

Section: Introductionmentioning

confidence: 99%

Influence of Loading a Tertiary Amine on Activated Carbons and Effect of CO₂ on Adsorptive H₂S Removal from Biogas

Quan

Jiang

Wang

et al. 2020

This work studied the influence of loading a tertiary amine on activated carbons (ACs) and the effect of CO2 on adsorptive H2S removal from biogas. After loading a tertiary amine, tetramethyl hexanediamine (THMDA), the H2S adsorption capacity increased for all ACs but with different levels. Detailed characterization results (TGA-MS, TGA/DTG, and in situ FT-IR) demonstrate the TMHDA-induced changes of surface oxygen or nitrogen functional groups, pH value, and textural properties and their impacts on H2S adsorption performance, which also varied with CO2 concentrations. On bare AC adsorbents, the H2S adsorption is attributed to the surface oxygen functional groups, whereas on tertiary amine-loaded ACs, the H2S adsorption is due to the interaction between H in H2S and N in the amine group. The presence of CO2 can promote H2S adsorption on some ACs and THMDA-loaded ACs. The formation of solid sulfur and CH4 was observed for the H2S adsorption in the presence of CO2.

“…Nonoxidative H 2 S decomposition, as illustrated in eq , is a promising strategy to overcome the drawbacks of oxidative schemes by yielding high-purity H 2 along with higher energy efficiency in sulfur recovery However, direct H 2 S decomposition in the gaseous phase is highly endothermic, and its reversible nature severely limits the equilibrium conversion. , To improve the H 2 yield, nonoxidative H 2 S decomposition using various approaches such as photocatalytic, electrochemical, and plasmolytic have been investigated. , Plasmolytic and electrochemical approaches are primarily constrained by inefficient H 2 yields and high energy demand; photocatalysis is attractive due to the use of renewable energy source, but its long-term stability is limited by sulfur poisoning on the catalyst or in the electrolyte. ,− …”

Section: Introductionmentioning

confidence: 99%

Mo-Doped FeS Mediated H₂ Production from H₂S via an In Situ Cyclic Sulfur Looping Scheme

Jangam

Chen

Fan

2021

Decomposition of H 2 S into sulfur and clean fuel H 2 is an attractive process and requires a design concept with a maximum H 2 S conversion and a minimal energy consumption. Herein, we demonstrate a sulfur looping scheme in a one-reactor system using a low-cost and environmentally safe iron-based sulfur carrier. H 2 S decomposition is split into cyclic sulfidation and regeneration of sulfur carriers, which overcomes the inherent thermodynamic constraint, allowing in situ H 2 generation. We experimentally obtained 24% higher sulfur uptake in 2% Mo-doped iron-based sulfur carriers compared with undoped sulfur carriers. The reaction mechanisms unveiled by the density functional theory indicate that surface hydrogen diffusion is the rate-determining step for sulfidation of the sulfur carrier. Compared with the undoped sulfur carrier, Mo dopant facilitates the surface hydrogen diffusion, thus promoting the overall H 2 S conversion. This work demonstrates a novel strategy for high-yielding H 2 S removal through low-percentage dopant modification sulfur carrier and provides new insights for an effective dopant screening strategy aiding the future carrier design.