Enabling direct-growth route for highly efficient ethanol upgrading to long-chain alcohols in aqueous phase.

Upgrading ethanol to long-chain alcohols (LAS, C6+OH) offers an attractive and sustainable approach to carbon neutrality. Yet it remains a grand challenge to achieve efficient carbon chain propagation, particularly with noble metal-free catalysts in aqueous phase, toward LAS production. Here we report an unconventional but effective strategy for designing highly efficient catalysts for ethanol upgrading to LAS, in which Ni catalytic sites are controllably exposed on surface through sulfur modification. The optimal catalyst exhibits the performance well exceeding previous reports, achieving ultrahigh LAS selectivity (15.2% C6OH and 59.0% C8+OH) at nearly complete ethanol conversion (99.1%). Our in situ characterizations, together with theoretical simulation, reveal that the selectively exposed Ni sites which offer strong adsorption for aldehydes but are inert for side reactions can effectively stabilize and enrich aldehyde intermediates, dramatically improving direct-growth probability toward LAS production. This work opens a new paradigm for designing high-performance non-noble metal catalysts for upgrading aqueous EtOH to LAS.

Alkali carbonate induced N-doped NiSn@NC for direct aqueous ethanol coupling to C6+ higher alcohols.

Synthesis of C6+ higher alcohols from readily-accessible aqueous ethanol is an alternative route of great potential for blending-fuel, plasticizer, surfactant and medicine precursors, but the direct coupling of aqueous ethanol to C6+ higher alcohols is still challenging. Herein, the alkali carbonate induced N-doping of a NiSn@NC catalyst was achieved by a facile gel-carbonization strategy, and the effect of alkali salt inductors was examined for the direct coupling of 50 wt% aqueous ethanol. Noteworthily, C6+ higher alcohol selectivity of 61.9% with 57.1% ethanol conversion was achieved for the first time over the NiSn@NC-Na2CO3-1/9 catalyst, which broke the step-growth carbon distribution of ethanol coupling to higher alcohols. The inductive effect of alkali carbonate for the N doped graphite structure from the NO3- precursor was revealed. Electron transfer from Ni to the pyridine N doped graphite layer is enhanced, thus elevating the Ni-4s band center, which lowers the dehydrogenation barrier of the alcohol substrate and further improves the C6+OH selectivity. The catalyst reusability was also examined. This work gained new insight into the selective synthesis of high-carbon value-added chemicals from C-C coupling of aqueous ethanol.

Graphene-like wrapped Ni@C catalyst with magnetic recyclability for selective hydrogenation of nitro-aromatics.

The graphene-like wrapped Ni@C catalysts were facilely synthesized by a modified sol-gel method. Nickel nitrate and citric acid (CA) were adopted as the raw materials to form sol-gel mixture. Under the circumstances, the additive CA were employed not only as a complexing agent but also as a carbon source. It is found that the calcination temperature and the mole ratios between Ni and CA are the key factors affecting the physical property and the catalytic performance of catalysts in the conversion of nitroarenes into corresponding anilines. The results show that the Ni@C-500(1:1) catalyst exhibited the best performance in the hydrogenation ofo-chloronitrobenzenes (o-CNB) too-chloroanilines (o-CAN). The yield ofo-CAN was achieved at 100% wheno-CNB was completely converted at 40.0 °C under 2.0 MPa H2for 2.0 h. Furthermore, the Ni@C-500(1:1) catalyst could be separated and recovered easily after reaction by an external magnetic field. The investigated results indicate that the Ni@C-500(1:1) catalyst remained higher activity after using twelve times. More importantly, this kind of catalyst is also active for the selective hydrogenation of other nitroarenes into the corresponding anilines. This new synthetic method may pave a way for producing low-cost Ni@C catalysts on a large scale, which is attractive for industrial anilines applications.

Surface Structure Engineering of PdAg Alloys with Boosted CO2 Electrochemical Reduction Performance.

Converting carbon dioxide into high-value-added formic acid as a basic raw material for the chemical industry via an electrochemical process under ambient conditions not only alleviates greenhouse gas effects but also contributes to effective carbon cycles. Unfortunately, the most commonly used Pd-based catalysts can be easily poisoned by the in situ formed minor byproduct CO during the carbon dioxide reduction reaction (CRR) process. Herein, we report a facile method to synthesize highly uniformed PdAg alloys with tunable morphologies and electrocatalytic performance via a simple liquid synthesis approach. By tuning the molar ratio of the Ag+ and Pd2+ precursors, the morphologies, composition, and electrocatalytic activities of the obtained materials were well-regulated, which was characterized by TEM, XPS, XRD, as well as electrocatalytic measurements. The CRR results showed that the as-obtained Pd3Ag exhibited the highest performance among the five samples, with a faradic efficient (FE) of 96% for formic acid at -0.2 V (vs. reference hydrogen electrode (RHE)) and superior stability without current density decrease. The enhanced ability to adsorb and activate CO2 molecules, higher resistance to CO, and a faster electronic transfer speed resulting from the alloyed PdAg nanostructure worked together to make great contributions to the improvement of the CRR performance. These findings may provide a new feasible route toward the rational design and synthesis of alloy catalysts with high stability and selectivity for clean energy storage and conversion in the future.

Facile fabrication of porous Fe@C nanohybrids from natural magnetite as excellent Fischer-Tropsch catalysts.

Fe-Based catalysts play crucial roles in Fischer-Tropsch synthesis (FTS). Herein, we for the first time demonstrate a facile sol-gel approach using natural magnetite and citric acid to fabricate porous Fe@C nanohybrids as FTS catalysts. Excellent FTS activity and stability were revealed and attributed to the formation of an Fe3C active phase and a core-shell structure. This flexible synthesis strategy clearly highlights the promising application of such materials in FTS.

High efficient conversion of CO2-rich bio-syngas to CO-rich bio-syngas using biomass char: a useful approach for production of bio-methanol from bio-oil.

A novel approach for high efficient conversion of the CO(2)-rich bio-syngas into the CO-rich bio-syngas was carried out by using biomass char and Ni/Al(2)O(3) catalyst, which was successfully applied for production of bio-methanol from bio-oil. After the bio-syngas conditioning, the CO(2)/CO ratio prominently dropped from 6.33 to 0.01-0.28. The maximum CO yield in the bio-syngas conditioning process reached about 1.96 mol/(mol CO(2)) with a nearly complete conversion of CO(2) (99.5%). The performance of bio-methanol synthesis was significantly improved via the conditioned bio-syngas, giving a maximum methanol yield of 1.32 kg/(kg(catalyst)h) with a methanol selectivity of 99%. Main reaction paths involved in the bio-syngas conditioning process have been investigated in detail by using different model mixture gases and different carbon sources.