Low-temperature Hydrogenation Research Articles

Life cycle assessment of emerging coal conversion technologies in China: An industrial-scale comparison

The continued large-scale industrialization of emerging coal conversion technologies (ECCTs) in China is an uncertain factor in the global de-coaling process. Its environmental impact is unclear or underestimated because of a lack of comprehensive and comparable studies. The objective of this study was to comprehensively quantify the environmental impacts of nine industrialized ECCTs in China to promote a shared understanding and facilitate discussion on this topic. A life cycle assessment (LCA) was used for modeling, and industrial added value was incorporated into the LCA model as a comparative benchmark for different ECCTs. The CML2001 method was used to model a localized LCA data inventory for representative projects. The results showed that medium- and low-temperature coal tar hydrogenation, coal to fuel ethanol, coal to ethylene glycol, and coal to olefins yielded lower environmental impacts than other ECCTs, and someone of the former three ECCTs was able to always exhibit the best competitiveness despite fluctuations in the feedstock product prices. The abiotic depletion potential of elements and the global warming potential was intensive in the material supply and feedstock conversion stages, respectively, and the majority of the other environmental impacts were derived from the feedstock and energy supply stages. If no mitigation strategies are implemented, carbon emissions caused by the industrialization of ECCTs may increase from 0.36 Gt CO2-eq at present to 1.02 Gt CO2-eq in 2030. This finding highlights the necessity of mitigating carbon emissions and calls for robust approaches to coordinate energy security and carbon neutrality.

Low-Temperature Acetylene Semi-Hydrogenation over the Pd1-Cu1 Dual-Atom Catalyst.

The atomically dispersed metal catalyst or single-atom catalyst (SAC) with the utmost metal utilization efficiency shows excellent selectivity toward ethylene compared to the metal nanoparticles catalyst in the acetylene semi-hydrogenation reaction. However, these catalysts normally work at relatively high temperatures. Achieving low-temperature reactivity while preserving high selectivity remains a challenge. To improve the intrinsic reactivity of SACs, rationally tailoring the coordination environments of the first metal atom by coordinating it with a second neighboring metal atom affords an opportunity. Here, we report the fabrication of a dual-atom catalyst (DAC) that features a bonded Pd1-Cu1 atomic pair anchoring on nanodiamond graphene (ND@G). Compared to the single-atom Pd or Cu catalyst, it exhibits increased reactivity at a lower temperature, with 100% acetylene conversion and 92% ethylene selectivity at 110 °C. This work provides a strategy for designing DACs for low-temperature hydrogenation by manipulating the coordination environment of catalytic sites at the atomic level.

β-Cyclodextrin promoted the formation of copper phyllosilicate on Cu-SiO2 microspheres catalysts to enhance the low-temperature hydrogenation of dimethyl oxalate

The formation of copper phyllosilicate is critical to the hydrogenation performance of Cu-SiO2 catalysts. A series of Cu-SiO2 microsphere catalysts modified with β-cyclodextrin (β-CD) prepared by the hydrothermal method were fabricated in this work. The results showed that Cu–β-CD complexes were favored to form during the hydrothermal process, which could promote the synthesis of copper phyllosilicate. Meanwhile, the introduction of an appropriate amount of β-CD also promoted the uniform dispersion of CuO species and reduced the size of copper nanoparticles. This could increase the ratio of Cu+/Cu0 after reduction. Thereby the synergistic effect between Cu0 and Cu+ and the stability of the catalyst could be enhanced. Eventually, the modified Cu-SiO2 microsphere catalyst exhibited better catalytic activity for hydrogenation of dimethyl oxalate to ethylene glycol. The dimethyl oxalate conversion of 99.9 % and ethylene glycol selectivity of 97.5 % could be obtained at a low temperature of 453 K. This work has considerable reference value for the subsequent construction of copper species on the catalyst surface.

Low-temperature hydrogenation of nanodiamond as a strategy to fabricate sp3-hybridized nanocarbon as a high-performance persulfate activator

This study presents the first instance of the application of hydrogenated nanodiamonds (H-NDs) for persulfate activation and the associated organic degradation. Surface hydrogenation at 600 ℃, confirmed by the increased surface density of the C-H moiety in XPS and FT-IR spectra, produced H-NDs that outperformed graphitized NDs (prepared via annealing at 1000 ℃) in terms of organic degradation and persulfate utilization efficiency. Hydrogenation improved the electrical conductivity of NDs; however, it was not accompanied by an increase in the sp2 carbon content − in contrast to energy-intensive ND graphitization − resulting from sp3-to-sp2 carbon transformation. In addition to the enhanced electron-transfer mediating activity, evidenced by the negative shift of the open circuit potential and current generation, isothermal titration calorimetry measurements indicated a significantly higher binding affinity of H-ND toward persulfate compared with that of graphitized ND. Multiple empirical results confirmed the progress of electron-transfer mediation as a major activation pathway.

Enhanced low-temperature CO2 methanation performance of Ni/ZrO2 catalysts via a phase engineering strategy

CO2 methanation is a promising route for converting CO2 into a marketable natural gas. The major challenge of this process is to enhance CO2 methanation catalytic activity at low temperature. This work showcases a supported-catalysts phase engineering strategy to overcome the challenge. We report a ∼ 24% decrease in the activation energy of methanation reaction over Ni/monoclinic-ZrO2 due to the optimization of ZrO2 crystal phases and thus turnover frequency of CO2 methanation at 240 °C increases by ∼ 116% than Ni/cubic-ZrO2. Both experimental characterizations and theoretical calculations confirm the high local electron density of Ni over Ni/monoclinic-ZrO2, a key factor to present superior performance for CO2 methanation, resulting from its high oxygen vacancies and electronic metal-support interactions. This is beneficial to the adsorption and dissociation of H2 and the hydrogenation of formate intermediate. Hence our work might open an avenue for rational design of advanced low-temperature CO2 hydrogenation catalysts via a phase engineering strategy.

Efficient low-temperature hydrogenation of fatty acids to fatty alcohols and alkanes on a Ni-Re bimetallic catalyst: The crucial role of NiRe alloys

Selective hydrogenation of fatty acids is important for production of sustainable fuels and valuable chemicals as well as for the utilization of natural oils and fats. Generally, high reaction temperature (>200 °C) is required due to the weak polarizability and low reactivity of the carbonyl group of fatty acids. Here, we report an efficient catalytic system (Ni-Re/SBA-15 bimetallic catalyst) that realizes the low-temperature conversion of fatty acids to corresponding alcohols (reaction temperature: 150 °C) and diesel-range alkanes (170 °C) with high yields, surpassing the catalytic performance rendered by most of the catalytic systems reported so far. Detailed investigation into the nature of the catalyst showed that the superior activity originated from the formation of NiRe alloy, which improved the dispersion of metallic Ni, the H2 activation ability and promoted the fatty acids/alcohols adsorption on the catalyst surface at low temperatures. More importantly, due to its strong electrophilicity, the fatty acids with highly electronegative carbonyl oxygen can be preferentially adsorbed on the catalyst surface than the fatty alcohols, which leads fatty acids to be converted preferentially. In this way, high catalytic efficiency and fatty alcohol selectivity can be obtained at a low temperature (150 °C). Further increasing reaction temperature to 170 °C, the reactant can be hydrodeoxygenated to form diesel-range alkanes. This developed NiRe/SBA-15 catalytic system highlights a great prospect for production of valuable fatty alcohols and alkanes from the conversion of bioderived fatty acids under mild conditions.

An efficient approach to biomass-based tertiary amines by direct and consecutive reductive amination of furfural

Tertiary amines, currently obtained from fossil resources by a multi-step synthetic method, are important compounds in both chemical industry and organic transformations. Herein, we demonstrated highly efficient and convenient strategy to various biomass-based tertiary amines in excellent yields (85–95%) by a direct and consecutive reductive amination of furfural with various amines in one-pot using rhodium phosphide (Rh2P) catalyst. Typically, biomass-based tris(2-furanylmethyl)amine in 92% yield was directly obtained from furfural and HCOONH4 in one-step. Time-dependent reaction profiles suggested a consecutive amination/hydrogenation pathway with furfurylamine-derived Schiff base and secondary amine as successively detected intermediates. The superiority of Rh2P was ascribed to its excellent low-temperature hydrogenation activity, which is structurally attributed to an efficient electron-transfer from P atoms (on the P-terminated Rh2P) to their bonded and dissociated H atoms. This research thus highlights a powerful, elegant, and attractive approach to biomass-based tertiary amines for a sustainable extension of amine chemistry.

H2 Plasma Reducing Ni Nanoparticles for Superior Catalysis on Hydrogen Sorption of MgH2

Highly fine, dispersive, and active catalysts are essential for lowering the operating temperature of MgH2, a promising high-capacity material for solid-state hydrogen storage. In this work, ultrafine Ni nanoparticles (2–6 nm) are synthesized from the precursor nickel acetylacetonate (C10H14NiO4) on the surface of MgH2 by H2 plasma reduction process, followed by further ball milling. The obtained composite could rapidly release more than 6.5 wt % H within 10 min at 275 °C. Even at a low temperature of 225 °C, up to 6 wt % H could be desorbed. The MgH2–Ni composite also exhibits excellent low-temperature hydrogenation kinetics and almost no capacity degradation over nine hydrogenation/dehydrogenation cycles. The significant improvement in the hydrogen-storage properties is attributed to the in situ formation of ultrafine and stable Mg2NiH0.3 nanocrystals during cycling. This work provides a convenient approach to synthesize ultrafine metal nanoparticles for catalytic applications in the field of high energy storage density hydride materials.

Effect of Surface Hydroxyl Content of Support on the Activity of Cu/ZSM-5 Catalyst for Low-Temperature Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

Effect of Surface Hydroxyl Content of Support on the Activity of Cu/ZSM-5 Catalyst for Low-Temperature Hydrogenation of Dimethyl Oxalate to Ethylene Glycol

Zif-8 Derived Zno@Nc Supported Ru Nanoparticles for Efficient Low-Temperature Hydrogenation of Levulinic Acid to Γ-Valerolactone

Zif-8 Derived Zno@Nc Supported Ru Nanoparticles for Efficient Low-Temperature Hydrogenation of Levulinic Acid to Γ-Valerolactone

Surface domain potential difference-mediated efficient charge separation on a defective ZnIn2S4 microsphere photocatalyst

Low-efficiency charge separation in metal sulfides is a major obstacle to realizing high photocatalytic performance. Herein, we propose the concept of a similar surface domain potential difference between adjacent microdomains with and without surface S vacancies on ZnIn2S4 to mediate charge separation. Defective ZnIn2S4 microspheres (DZISNPs) are prepared through a solvothermal method combined with a low-temperature hydrogenation surface engineering strategy. The as-prepared DZISNPs with a narrowed bandgap of 2.38 eV possess a large specific surface area of 178.5 m2 g−1, a pore size of 6.89 nm, and a pore volume of 0.36 cm3 g−1, which further improves the visible light absorption. The resultant DZISNPs exhibit excellent visible light activity (2.15 mmol h−1 g−1), which is ∼two-fold higher than that of the original DZISNP. The experimental results and DFT calculations reveal that the enhanced property can be a result of the surface S vacancy-induced surface domain potential difference, promoting the spatial separation of electrons and holes. Furthermore, the long-term stability of the DZISNPs indicates that the formation of surface S vacancies can inhibit the photocorrosion of ZnIn2S4. This strategy provides new insights for fabricating highly efficient and stable sulfide photocatalysts.

Liquid-phase methane bubble plasma discharge for heavy oil processing: Insights into free radicals-induced hydrogenation

Hydrogenation, an alternative to conventional cracking, is poised to revolutionize heavy oil upgrading by raising the hydrogen-to-carbon ratio at lower process pressures and temperatures. The emerging low-temperature plasma-enabled hydrogenation is an effective, fast, and environment-friendly process; however, the conversion rate and energy efficiency are still insufficient. To address these limitations, here we propose an innovative bubble-assisted methane plasma-liquid process for heavy oil processing (using ethylbenzene as a model compound) and offer new insights into radical-assisted hydrogenation. Results from the plasma kinetics modeling and density functional theory calculations indicate that ·H and ·CH3 radicals generated by CH4 plasma are two main drivers for ethylbenzene hydrogenation, and their chemical reaction rates with ethylbenzene molecules strongly depend on their spatial distribution in bubbles, which further govern the reaction direction towards ethylbenzene hydrogenation or free radical recombination. Moreover, it is found that by controlling the bubble numbers and plasma parameters, the H density can increase by an order of magnitude from 1.4 × 1020 to 3.88 × 1021 m−3, while the number of hydrogenated aromatic rings increases by ∼ 58%, which further confirms the excellences of the proposed plasma-bubble technology in chemical regulation and feasible processing. In addition, the feasibility of the plasma-enabled hydrogenation has been verified by the experiment, which highlighted the competition between the radical recombination and radical-aromatic ring interactions. Overall, the revealed interaction mechanisms between the plasma-generated radicals and ethylbenzene provide new insights and guiding principles for the future upgrading of heavy oils and other industrial hydrocarbon products.

Low-Temperature Hydrogenation of Iron Carbonate Followed By Production of C4-C6 Hydrocarbons

Low-Temperature Hydrogenation of Iron Carbonate Followed By Production of C4-C6 Hydrocarbons

Construction of bifunctional single-atom catalysts on the optimized β-Mo2C surface for highly selective hydrogenation of CO2 into ethanol

Green and economical CO2 utilization is significant for CO2 emission reduction and energy development. Here, the 1D Mo2C nanowires with dominant (101) crystal surfaces were modified by the deposition of atomic functional components Rh and K. While unmodified β­Mo2C could only convert CO2 to methanol, the designed catalyst of K0.2Rh0.2/β-Mo2C exhibited up to 72.1% of ethanol selectivity at 150 °C. It was observed that the atomically dispersed Rh could form the bifunctional active centres with the active carrier β­Mo2C with the synergistic effects to achieve highly specific controlled C–C coupling. By promoting the CO2 adsorption and activation, the introduction of an alkali metal (K) mainly regulated the balanced performance of the two active centres, which in turn improved the hydrogenation selectivity. Overall, the controlled modification of β­Mo2C provides a new design strategy for the highly efficient, low-temperature hydrogenation of CO2 to ethanol with single-atom catalysts, which provides an excellent example for the rational design of the complex catalysts.

(Invited) Catalysts for Low-Temperature Electrochemical Hydrogen Production and Hydrogenation Reactions

Electrochemical transformation of molecules is not only a low-carbon approach for producing valuable chemicals and fuels, but also a long-duration energy storage solution at scale for renewable power. Materials development especially electrocatalysts plays a critical role in enabling these processes with high efficiency. In this paper, we will present our recent progress on catalyst development for electrochemical hydrogen production and hydrogenation reactions. We will discuss hydrogen evolution reaction (HER) catalysts based on both platinum group metals (PGM) and earth abundant elements in various pH conditions, with a emphasis on the synergy between different components within certain catalysts in hope to reveal new mechanisms for catalyst design and development. We will also discuss electrocatalytic hydrogenation (ECH) of organic molecules from e.g., biomass. From these studies, we observed some correlation between different reactions which may be useful to bridge heterogenous and homogenous electrocatalytic reaction processes and promote catalyst design in both fields.

Low-Temperature Hydrogenation of Toluene Using an Iron-Promoted Molybdenum Carbide Catalyst

As an alternative to noble metal hydrogenation catalysts, pure molybdenum carbide displays unsatisfactory catalytic activity for arene hydrogenation. Precious metals such as palladium, platinum, and gold are widely used as additives to enhance the catalytic activities of molybdenum carbide, which severely limits its potential applications in industry. In this paper, iron-promoted molybdenum carbide was prepared and characterized by various techniques, including in situ XRD, synchrotron-based XPS and TEM. while the influence of Fe addition on catalytic performance for toluene hydrogenation was also studied. The experimental data disclose that a small amount of Fe doping strongly enhances catalytic stability in toluene hydrogenation, but the catalytic performance drops rapidly with higher loading amounts of Fe.

Highly effective microwave plasma application for catalyst-free and low temperature hydrogenation of biodiesel

Partially hydrogenated biodiesel or partially hydrogenated fatty acid methyl ester (H-FAME) derived from palm oil has been successfully synthesized using a microwave plasma system equipped with negative high voltage at low temperature without the use of a catalyst. The impact of the process parameters such as hydrogen gas feed flow rate, microwave power, reaction temperature, negative high voltage and reaction time on FAME composition and product properties were studied. It was found that the optimal condition for the highest conversion of polyunsaturated FAMEs was 8.5 L/min hydrogen flow rate, 500 W microwave power, 30 °C reaction temperature, 60 kV negative high voltage and 3 h of reaction time. The oxidation stability increased from 12.5 to 21.6 h and no trans C18:1 formation was detected. Further we found that the microwave plasma system equipped with negative high voltage can also be applied to effectively hydrogenate other chemicals at low temperatures without using a catalyst.

O, S-Dual-Vacancy Defects Mediated Efficient Charge Separation in ZnIn2S4/Black TiO2 Heterojunction Hollow Spheres for Boosting Photocatalytic Hydrogen Production.

Defective ZnIn2S4 nanosheets/mesoporous black TiO2 heterojunction hollow spheres (H-ZIS/b-TiO2) are prepared through hydrothermal and surface low-temperature hydrogenation strategies, which show broad-spectrum response and excellent charge separation efficiency. This H-ZIS/b-TiO2 flower-like heterojunction hollow spheres with a narrow band gap of ∼1.88 eV expand the light response to visible light and show excellent photocatalytic hydrogen evolution rate (278 μmol h-1 50 mg-1) under visible-light irradiation, which is 1.5 times as high as that of ZnIn2S4/black TiO2 heterojunction hollow spheres (ZIS/b-TiO2) (181 μmol h-1 50 mg-1). The excellent photocatalytic performance is due to the formation of O, S dual vacancies in b-TiO2 and H-ZIS providing more active sites for photocatalytic reaction and improving the charge separation efficiency, heterojunctions promoting transport of photogenerated carriers, and the hollow structure increasing light utilization by reflecting light. The novel heterojunction hollow sphere with high performance has broad application prospects in the field of energy.

Low-temperature hydrogenation of Mg-Ni-Nb2O5 alloy processed by high-pressure torsion

Powder mixtures with a nominal composition Mg-5 wt%Ni-2 wt%Nb2O5 are used to produce ultrafine-grained bulk material by high-pressure torsion (HPT) processing. Samples subjected to 10 and 20 revolutions in torsion under a pressure of 3 GPa developed an ultrafine grain size, mainly in the 100−200 nm range. The hydrogenation properties of these HPT-processed materials have been characterized at temperatures in the interval of 373–723 K. The hydrogenation experiments clearly show faster kinetics of hydrogenation and higher storage capacities in the HPT materials compared to the initial mild-milled powder mixture. The storage capacities have been limited to about 5.5 wt% H2 by the formation of a substantial amount of MgO in the materials after several hydrogenation cycles. However, as a matter of practical relevance, the production of bulk pieces of the Mg-Ni-Nb2O5 alloy having an ultrafine grain structure allows handling of the material without special precautions against ignition, as well as its storage in contact with air for several months with no evident deterioration of its fast activation in posterior hydrogenation treatments.

Synthesis of a high surface area and highly dispersed Cu-O-Si complex oxide used for the low-temperature hydrogenation of dimethyl oxalate to ethylene glycol

A highly dispersed Cu-O-Si composite oxide framework catalyst with high surface area (619 m2/g) and very small particle size (~3 nm) has been synthesized using an improved precipitation method, which showed high catalytic activity toward the hydrogenation of dimethyl oxalate (DMO) (99.9% conversion of DMO and 96.7% selectivity for ethylene glycol) even at low temperature (175 °C). In addition, its chemical stability was significantly enhanced due to the formation of a Cu-O-Si composite structure and the low reaction temperature, and the catalyst did not show any significant inactivation during the stability test over 140 h.