Baoning Zong

FexOy@C Spheres as an Excellent Catalyst for Fischer−Tropsch Synthesis

We demonstrate a one-pot hydrothermal cohydrolysis-carbonization process using glucose and iron nitrate as starting materials for the fabrication of carbonaceous spheres embedded with iron oxide nanoparticles. It is verified by TEM, (57)Fe Mossbauer, and Fe K-edge XAS that iron oxide nanoparticles are highly dispersed in the carbonaceous spheres, leading to a unique microstructure. A formation mechanism is also proposed. This route is also applicable to a range of other naturally occurring saccharides and metal nitrates. A catalytic study revealed the remarkable stability and selectivity of the reduced Fe(x)O(y)@C spheres in the Fischer-Tropsch synthesis, which clearly exemplifies the promising application of such materials.

Size-controlled nitrogen-containing mesoporous carbon nanospheres by one-step aqueous self-assembly strategy

Nitrogen-containing mesoporous carbon nanospheres with tunable sizes have been prepared through an aqueous self-assembly process with F127 as a template and morphological control agent, and 3-aminophenol as carbon and nitrogen sources. The sphere sizes could be simply tuned by optimizing the concentration of F127 and ammonia. Compared with a traditional nanocasting method and a hydrothermal process, the present one-step method has the striking features of a simple synthesis process and easy introduction of the nitrogen atom into the carbon nanospheres. The feasibility of the fabrication method may open up a new way for the synthesis of heteroatom-containing carbon nanospheres with mesoporous structure. The prepared nitrogen-containing mesoporous carbon nanospheres exhibit good catalytic performance in the direct dehydrogenation of ethylbenzene due to their unique mesostructure and abundant oxygen and nitrogen functional groups.

ε -Iron carbide as a low-temperature Fischer–Tropsch synthesis catalyst

ε-Iron carbide has been predicted to be promising for low-temperature Fischer-Tropsch synthesis (LTFTS) targeting liquid fuel production. However, directional carbidation of metallic iron to ε-iron carbide is challenging due to kinetic hindrance. Here we show how rapidly quenched skeletal iron featuring nanocrystalline dimensions, low coordination number and an expanded lattice may solve this problem. We find that the carbidation of rapidly quenched skeletal iron occurs readily in situ during LTFTS at 423-473 K, giving an ε-iron carbide-dominant catalyst that exhibits superior activity to literature iron and cobalt catalysts, and comparable to more expensive noble ruthenium catalyst, coupled with high selectivity to liquid fuels and robustness without the aid of electronic or structural promoters. This finding may permit the development of an advanced energy-efficient and clean fuel-oriented FTS process on the basis of a cost-effective iron catalyst.

A highly selective Raney Fe@HZSM-5 Fischer–Tropsch synthesis catalyst for gasoline production: one-pot synthesis and unexpected effect of zeolites

A novel Raney Fe@HZSM-5 Fischer–Tropsch synthesis catalyst was synthesized via a facile one-pot strategy using an FeAl alloy as the Fe precursor and as the Al source. Aside from cracking/isomerization of heavy hydrocarbons, HZSM-5 also stabilizes Hagg carbide, resulting in excellent selectivity to gasoline fraction and unexpectedly enhanced C5+ selectivity.

An environmentally benign and catalytically efficient non-pyrophoric Ni catalyst for aqueous-phase reforming of ethylene glycol

A non-pyrophoric Ni catalyst (NP Ni) was prepared by alkali leaching of a Ni50Al50 alloy using only ∼ 1/10 of the amount of NaOH required for the preparation of the conventional Raney Ni catalyst. Characterizations reveal that the as-prepared NP Ni catalyst can be looked at as a Ni–Al(OH)3 composite catalyst with Ni in the metallic state and Al(OH)3 in forms of gibbsite and bayerite. After 100 h on stream in aqueous-phase reforming (APR) of ethylene glycol, phase transformation of gibbsite and bayerite to flake-like boehmite occurred, along with the growth of Ni crystallites and partial oxidation of metallic Ni to Ni(OH)2. Under identical reaction conditions for APR of ethylene glycol, the NP Ni catalyst is about 40–52% more active than Raney Ni in terms of the conversion of ethylene glycol to gas products, which is attributed to the stabilizing effect of hydrated alumina on Ni crystallites. The higher selectivity toward H2 and the lower concentration of CO in the product gas on the NP Ni catalyst are attributed to the activation of water by hydrated alumina which is beneficial to the water-gas shift reaction.

Factors in mass cultivation of microalgae for biodiesel

Abstract Biofuel from microalgae is a long term strategy to solve the energy crisis. It is a new area of biological engineering and process engineering that consists of the isolation and characterization of microalgae species, mass cultivation of microalgae, harvesting and post-processing. The successful mass cultivation of microalgae is one of its main challenges. Several factors influencing the mass cultivation of microalgae are discussed, such as microalgae species, metabolic mechanism, culture conditions and the photobioreactor. This paper will help the development of biofuels from microalgae and its photobioreactor.

Nitrobenzene reduction catalyzed by carbon: does the reaction really belong to carbocatalysis?

The reduction of nitrobenzene could proceed in the presence of carbon. The activity mainly originated from carbonyl groups on the carbon surface instead of metal impurities which were embedded in the carbon.

Physically mixed ZnO and skeletal NiMo for one-pot reforming-hydrogenolysis of glycerol to 1,2-propanediol

Abstract The one-pot aqueous phase reforming (APR) and hydrogenolysis of glycerol to 1,2-propanediol (PDO) was catalyzed by physically mixed skeletal NiMo and zinc oxide catalysts in a continuous flow fixed-bed reactor without the aid of added H2. The skeletal NiMo catalyst alone is highly active towards glycerol but the selectivity for 1,2-PDO is only moderate. Physically mixing of MgO, SiO2, Al2O3, HZSM-5, TiO2, ZrO2, or CeO2 as a cocatalyst with skeletal NiMo was detrimental to the conversion of glycerol and yield of 1,2-PDO. However, physically mixing with ZnO gave an advantageous promoting effect on both the catalytic activity and selectivity for 1,2-PDO, and gave a 1,2-PDO yield of 52.0%, which is higher than that obtained with noble metal catalysts for the APR-hydrogenolysis of glycerol. The synergistic effect between physically mixed ZnO and skeletal NiMo was attributed to in situ enhancement of the Lewis acidity of ZnO by chemisorbed CO2 from the APR of glycerol on skeletal NiMo, which benefited both the dehydration of glycerol to acetol on ZnO and the hydrogenation of acetol to 1,2-PDO on skeletal NiMo.

One‐Pot Approach to a Highly Robust Iron Oxide/Reduced Graphene Oxide Nanocatalyst for Fischer–Tropsch Synthesis

Graphene is a two-dimensional single-layer sheet of graphite with p electrons fully delocalized on the graphitic basal plane. For physicists, the high lattice perfection of graphene is appealing, because it allows exceptional mobility of charge carriers, it shows superior thermal conductivity, and it displays fascinating quantum Hall effects, all of which promote the fascinating functionalities of graphene-based devices . For chemists, perfect graphene is too “slippery”, as it is difficult for metal/metal oxide nanoparticles (NPs) deposited on its surface to keep their original size at elevated temperatures as a result of weak van der Waals interactions of graphene and the high surface energy of the NPs. Theoretical calculations revealed low activation energies (0.14–0.8 eV) for the diffusion of metal atoms on perfect graphene. The high mobility of the atoms on graphene may explain the predominant utilization of metal/metal oxide NPs–graphene hybrid materials in ambientor moderate-temperature processes. Recently, by utilizing deviations from perfect graphene, that is, graphene having oxygen-containing groups and atomic defects, Dai and coworkers designed a two-step method that can limit the dimension of the metal oxide NPs to approximately 5 nm on reduced graphene oxide (rGO) by hydrothermal treatment at 453 K. 5b, d, 9a] However, doubt surrounding the thermal stability of such small metal/metal oxide NPs on graphene at elevated temperatures over the long term remains, which shadows the prospect of using these new graphene-relating materials in practical applications. Although wrapping of the metal/metal oxide NPs by graphene 9d, e] may physically restrict them from aggregating, the graphene overlayer is expected to cover the active sites and thus deteriorate the catalytic efficiency in heterogeneous catalysis. Herein, we demonstrate a facile one-pot hydrothermal hydrolysis–reduction (HHR) strategy that is able to fabricate gFe2O3 NPs that are sub-3 nm in size that are highly dispersed on rGO by using iron(III) acetylacetonate [Fe(acac)3] and graphene oxide (GO) as starting materials (Scheme 1). This Fe–rGO nanohybrid material exhibited impressively high thermal stability in high-temperature reduction at 723 K for 16 h and in a successive long-term Fischer–Tropsch synthesis (FTS) reaction at 543 K. Moreover, the Fe–rGO nanohybrid afforded much higher FTS activity and better selectivities for C5 + and C5–C11 hydrocarbons (gasoline fraction) than Fe/p-rGO, which was fabricated by using prereduced graphene oxide (p-rGO) instead of GO as the starting material (also illustrated in Scheme 1), and Fe/AC, which was prepared with commercial Vulcan X-72 activated carbon (AC) as the support. We further validated that the one-pot HHR strategy can be extended to the fabrication of other metal-oxide-on-graphene materials with small and uniform particle sizes. During the preparation, GO was synthesized according to the modified Hummers method from natural flake graphite. Then, Fe(acac)3 was mixed with an aqueous suspension of GO

Structural and Catalytic Properties of Alkaline Post‐Treated Ru/ZrO2 Catalysts for Partial Hydrogenation of Benzene to Cyclohexene

Partial hydrogenation of benzene to cyclohexene is attractive in terms of feedstock accessibility, atomic economy, and operational simplicity. Herein, a series of Ru/ZrO2 catalysts were prepared by post‐treatment of a binary Ru–Zn/ZrO2 catalyst using 5–30 wt % NaOH aqueous solutions. Alloying between Ru and Zn was evidenced for the catalyst post‐treated only by water (Ru/ZrO2‐0). Alkaline post‐treatment removed metallic Zn, forming smaller Ru nanoparticles. Concomitantly, the hydrophilicity of the catalysts was increased and maximized on the 10 wt % NaOH‐treated catalyst (Ru/ZrO2‐10). In partial hydrogenation of benzene, the Ru/ZrO2‐0 catalyst displayed the highest turnover frequency but the lowest initial selectivity to cyclohexene, whereas the Ru/ZrO2‐10 catalyst exhibited the highest initial selectivity (86 %) and yield of cyclohexene (51 %) among the catalysts investigated. A quantitative relationship between the initial selectivity to cyclohexene and the hydrophilicity of these catalysts was identified, which rationalizes the significant impact of alkaline post‐treatment on selectivity enhancement in partial hydrogenation of benzene to cyclohexene over Ru/ZrO2 catalysts.