The study of the performance of PtNi/CeO2–nanocube catalysts for low temperature steam reforming of ethanol

A mini review on recent progress of steam reforming of ethanol

H2 is one of the promising renewable energy sources, but its production and transportation remain challenging. Distributed H2 production using liquid H2 carriers is one of the ideal ways of H2 utilization. Among common H2 carriers, ethanol is promising as it has high H2 content and can be derived from renewable bio-energy sources such as sucrose, starch compounds, and cellulosic biomass. To generate H2 from ethanol, steam reforming of ethanol (SRE) is the most common way, while appropriate catalysts, usually supported metal catalysts, are indispensable. However, the SRE process is quite complicated and always accompanied by various undesirable by-products, causing low H2 yield. Moreover, the catalysts for SRE are easy to deactivate due to sintering and carbon deposition under high reaction temperatures. In recent years, lots of efforts have been made to reveal SRE mechanisms and synthesize catalysts with high H2 yield and excellent stability. Both active metals and supports play an important role in the reaction. This mini-review summarizes the recent progress of SRE catalysts from the view of the impacts of active metals and supports and draws an outlook for future research directions.

Efficient Catalysts of Ethanol Steam Reforming Based on Perovskite-Fluorite Nanocomposites with Supported Ni: Effect of the Synthesis Methods on the Activity and Stability

Catalysts based on perovskite—fluorite nanocomposites with supported nickel 5%Ni/[Pr0.15Sm0.15Ce0.35Zr0.35O2 + LaMn0.9Ru0.1O3] were synthesized by three different methods. Structural and surface features of as-prepared samples were elucidated by N2 adsorption, XRD, HR TEM with EDX; reducibility and reactivity were estimated by H2-TPR, and catalytic properties were studied in ethanol steam reforming in the 500–700 °C temperature range. The best catalytic activity without coke accumulation was demonstrated for the 5%Ni/[Pr0.15Sm0.15Ce0.35Zr0.35O2+ LaMn0.9Ru0.1O3] catalyst with nanocomposite support obtained by a simple sequential polymeric preparation method. Highly dispersed particles of metallic nickel strongly fixed on the support after the reaction were shown by the HR-TEM and H2 –TPR data. The catalyst provides stable full conversion of ethanol and hydrogen yield above 60% at 600 °C for at least 6 h.

Hydrogen Production through Autothermal Reforming of Ethanol: Enhancement of Ni Catalyst Performance via Promotion

Autothermal reforming of bioethanol (ATR of C2H5OH) over promoted Ni/Ce0.8La0.2O1.9 catalysts was studied to develop carbon-neutral technologies for hydrogen production. The regulation of the functional properties of the catalysts was attained by adjusting their nanostructure and reducibility by introducing various types and content of M promoters (M = Pt, Pd, Rh, Re; molar ratio M/Ni = 0.003–0.012). The composition–characteristics–activity correlation was determined using catalyst testing in ATR of C2H5OH, thermal analysis, N2 adsorption, X-ray diffraction, transmission electron microscopy, and EDX analysis. It was shown that the type and content of the promoter, as well as the preparation mode (combined or sequential impregnation methods), determine the redox properties of catalysts and influence the textural and structural characteristics of the samples. The reducibility of catalysts improves in the following sequence of promoters: Re < Rh < Pd < Pt, with an increase in their content, and when using the co-impregnation method. It was found that in ATR of C2H5OH over bimetallic Ni-M/Ce0.8La0.2O1.9 catalysts at 600 °C, the hydrogen yield increased in the following row of promoters: Pt < Rh < Pd < Re at 100% conversion of ethanol. The introduction of M leads to the formation of a NiM alloy under reaction conditions and affects the resistance of the catalyst to oxidation, sintering, and coking. It was found that for enhancing Ni catalyst performance in H2 production through ATR of C2H5OH, the most effective promotion is with Re: at 600 °C over the optimum 10Ni-0.4Re/Ce0.8La0.2O1.9 catalyst the highest hydrogen yield 65% was observed.

Copper Tricomponent Catalysts Application for Hydrogen Production from Ethanol

The application of copper-based catalysts in the production of pure hydrogen in the steam reforming of ethanol was performed. The tricomponent Cu/Zr catalysts with about 4 mass% addition of nickel, cobalt, or cerium have been prepared in our laboratory. The properties of obtained catalysts were compared with bimetallic Cu/Zr catalyst prepared and tested according to the same procedure. Catalytic tests were carried out in the continuous flow fixed–bed reactor in the wide temperature range of 433–593 K for initial molar ratio of ethanol to water equal to 1:3. Catalysts were characterized by XRD, TPR, CO2–TPD, and TPO methods. Cu/Zr/Ce catalyst proved to be the best; hydrogen yield reached the value of 400 L/(kgcat.∙h), selectivity towards carbon monoxide was below 0.5% and the one towards methane wasnot detected. Additions of Ni or Co did not bring significant improvement in activity.

Pt-Ni/ZnO-rod catalysts for hydrogen production by steam reforming of methanol with oxygen

Ni, Pt and a mixture of Ni and Pt supported on ZnO-rods were evaluated in autothermal steam reforming of methanol (ASRM) for hydrogen production as a function of the reaction temperature. The catalytic materials were characterized by SEM-EDS, XRD, TEM, HRTEM, TPR and BET. Analysis by SEM and TEM showed structural modifications on the surface of the ZnO rods after Ni impregnation. The reactivity of the catalytic materials in the range of 200–500 °C showed that the bimetallic sample had better catalytic activity among all the catalysts studied. This finding could be associated to PtZn and NiZn alloys present in this catalyst, which were identified by XRD and HRTEM analyses. Catalyst characterization by XRD after the catalytic testing showed that the intermetallic PtZn phase was stable during the reaction in the Pt/ZnO-rod sample. The cubic Ni_0.75–Zn_0.25 structure identified in the Ni/ZnO-rod sample was transformed to Zn_0.1–Ni_0.9–O and metallic Ni phases, respectively. On the bimetallic PtNi/ZnO-rod sample, the cubic Ni_0.75–Zn_0.25 structure remained, although the tetragonal NiZn structure is unstable and was destroyed during the ASRM reaction and then a new phase of Ni_0.7Pt_0.3 emerged. The promotion effect of Pt and/or Ni on the ZnO-rod was clearly shown.

PtZn and NiZn alloys on ZnO-1D samples were evaluated in the ASRM. Bifunctional behavior between PtZn, NiZn alloys and the ZnO were reported. The ZnO provides the adsorption sites for the reagents and the alloy particles facilitate the H₂ transfer.

Bioalcohol Reforming: An Overview of the Recent Advances for the Enhancement of Catalyst Stability

The growing demand for energy production highlights the shortage of traditional resources and the related environmental issues. The adoption of bioalcohols (i.e., alcohols produced from biomass or biological routes) is progressively becoming an interesting approach that is used to restrict the consumption of fossil fuels. Bioethanol, biomethanol, bioglycerol, and other bioalcohols (propanol and butanol) represent attractive feedstocks for catalytic reforming and production of hydrogen, which is considered the fuel of the future. Different processes are already available, including steam reforming, oxidative reforming, dry reforming, and aqueous-phase reforming. Achieving the desired hydrogen selectivity is one of the main challenges, due to the occurrence of side reactions that cause coke formation and catalyst deactivation. The aims of this review are related to the critical identification of the formation of carbon roots and the deactivation of catalysts in bioalcohol reforming reactions. Furthermore, attention is focused on the strategies used to improve the durability and stability of the catalysts, with particular attention paid to the innovative formulations developed over the last 5 years.

Syngas production by partial oxidation of ethanol on PtNi/SiO2–CeO2 catalysts

Syngas production from the partial oxidation of (bio)ethanol (POE) was demonstrated.

Effect of Pretreatment on the Adsorption Performance of Ni/ZnO Adsorbent for Dibenzothiophene Desulfurization

Ni/ZnO was prepared by co-precipitation and used as adsorbent for reactive adsorption desulfurization (RADS) of dibenzothiophene. The effect of calcination temperature, precipitate washing solvent, and reduction temperature on the adsorption performance of Ni/ZnO was investigated. It is observed that Ni/ZnO adsorbent calcined at 350 °C, washed with ethanol, and unreduced or reduced at low temperature performed best. By the characterization of BET, XRD, TPR, FTIR, and in situ XAFS, the optimal calcination temperature leads to the small crystallite of NiO and ZnO species. Washing with ethanol enhances the surface area of adsorbent and decreases its particle size. The influence of reduction temperature on the RADS performance is stronger than that of calcination temperature, which is ascribed to high-temperature reduction that makes the adsorbent easier to sinter and form a Ni-Zn alloy. The high RADS activity is a result of the adsorbent pretreatment conditions, which can form small Ni and ZnO particles, and the synergism between precursors.

A novel BEA-type zeolite core–shell multiple catalyst for hydrogen-rich gas production from ethanol steam reforming

BEA-type core–shell catalysts consisting of a core supporting Cu and Fe and a Ni-based shell were investigated for their ethanol steam reforming (ESR) activity.

Synthesis of Pt3Ni microspheres with high performance for rapid degradation of organic dyes

In this study, Pt3Ni microspheres consisted of nanoparticles were synthesized without addition of surfactants via the solvothermal route. The obtained sample was characterized by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FESEM). Furthermore, the catalytic performance of as-synthesized Pt3Ni microspheres was evaluated on the degradation of different organic dyes (methylene blue, methyl orange, Congo red, and rhodamine B). The results show that different dyes were rapidly decomposed by Pt3Ni microspheres in different pathways. Among different dyes, the formation and further degradation of the intermediates was observed during the degradation of methylene blue and methyl orange, suggesting the indirect degradation process of these dyes. This study provides not only a promising catalyst for the removal of organic contaminants for environment remediation, but also new insights for Pt3Ni alloy as a high-performance catalyst in organic synthesis.

Self-assembly of cuprous oxide nanoparticles supported on reduced graphene oxide and their enhanced performance for catalytic reduction of nitrophenols

Mechanism for the catalytic reduction of nitrophenols; the catalyst can be reused with nearly invariable high catalytic efficiency.