Hydrogen production from steam reforming of phenol over supported nickel-cobalt catalyst

This thesis presents the results of a study of catalytic phenol steam reforming with the aim of hydrogen production using bimetallic nickel-cobalt (Ni-Co) supported on cerium oxide, zirconium dioxide (ZrO2), lanthanum oxide, gamma alumina, and alpha alumina catalysts. Phenol has been selected as a reactant due to the high amount of phenol in bio-oil and is a potential renewable feedstock for hydrogen production. The high cost of noble based catalysts, low activity and performance of non-noble based catalysts, deactivation of catalysts by coke formation, and high temperature requirements for complete phenol conversion are the problems of the previous research. The aim of this research is to develop a highly active and stable catalyst for hydrogen production from the steam reforming of phenol. The physical and chemical properties of the catalysts were characterized in terms of their surface area, crystallinity, reducibility, acidity, basicity, and coke formation. Five prepared catalysts were screened by using a micro-reactor fixed bed at a temperature of 650 oC and atmospheric pressure. The effect of Ni to Co ratio on hydrogen production from phenol steam reforming reaction was then investigated. This was followed by parametric study on the process involving five factors, namely temperature (A), feed flow rate (B), catalyst amount (C), presence of Ni and Co (D), as well as concentration of phenol (E), and the two responses were phenol conversion (Y1) and hydrogen (Y2). The optimum catalytic performance was found to be for the Ni-Co/ZrO2 catalyst with 81.9% of phenol conversion and 80.7% of hydrogen yield at 650 oC. The effect of Ni to Co metal ratio study showed that the 75 wt.% Ni-25 wt.% Co supported on ZrO2 catalyst displayed a superior catalytic activity among all the ratios. The parametric analysis showed that five variables (A, B, C, D and E) and interactions among AE, BE and DE produced significant effects on Y1 and Y2. In the kinetic study, the results suggested that the surface reaction was the rate limiting step by assuming non-dissociative adsorption of phenol and steam using this catalyst. Hence, it is concluded that bimetallic Ni-Co supported on ZrO2 catalyst is able to produce high hydrogen yield and has the potential to tackle the catalyst deactivation by coke

Recent advancements of layered double hydroxide heterojunction composites with engineering approach towards photocatalytic hydrogen production: A review

Photocatalytic hydrogen production has been considered as one of the most promising alternatives for providing clean, sustainable, and renewable energy sources. Tremendous investigation and efforts have been devoted to increase the efficiency of the solar to energy conversion of a photocatalyst. Layered double hydroxide (LDH) received scientific attention for its excellent compositional flexibility and controllable morphology, leading to the facile incorporation of the metal species into their layered structure. The unique multi-structure and the tunability of its band gap make LDH more prominent in the field of photocatalysis. This article highlights the recent developments in the fabrication of LDH-based photocatalyst nanocomposites and the engineering approaches for augmenting their photocatalytic hydrogen production efficiency. The thermodynamics and challenges in photocatalytic water splitting are deliberated to understand the pathways to construct efficient semiconductor photocatalysis system. The efficiency enhancement of LDH-based photocatalysts are comprehensively discussed by giving special attention to the heterojunction engineering of type I, type II, p-n junction, Z-scheme, S-scheme, and R-scheme. Fabrication of the hybrid LDH nanocomposites through band gap engineering and metal loading are summarised. The architectural and morphological tuning of LDH-based composite through the construction of the novel core-shell structure and layer-by-layer nanosheets are also demonstrated. Finally, the future recommendations are outlined to provide insights for their development in the photocatalysis field

Hydrogen and value-added liquid fuel generation from pyrolysis-catalytic steam reforming conditions of microplastics waste dissolved in phenol over bifunctional Ni-Pt supported on Ti-Al nanocatalysts

This research looks at the potential of utilizing microplastics waste (MPW) found in oceans and soil as a source of liquid fuel. A significant portion of this pollutant is presently untreated and ends up in landfills, exacerbating the worldwide issue of marine and land pollution. Pyrolysis is a tertiary recycling process that is presented as a solution in the presence of a catalyst. This study aimed to develop bifunctional Ni-Pt nanocatalysts supported on TiO2 and Al2O3 for hydrogen and valued fuels generation from pyrolysis-catalytic steam reforming conditions of microplastics waste dissolved in phenol. The chemical and physical properties of nanocatalysts were characterized by BET, XRD, TEM, FESEM, FTIR, H2-TPR, CO2-TPD, NH3-TPD, TGA, ICP and CHNS. It was found that the introduction of a small portion of Pt (2 wt%) metal to the Ni/Ti-Al nanocatalyst was found to significantly enhance the reducibility, acidity, basicity nanocatalyst performance and stability. C–O(H), C[dbnd]C–C, and C–O were the major functional clusters of the liquid yields surveyed from the FTIR spectrums during pyrolysis. A valuable liquid product such as trimethyl-(2-trimethylsilylphenyl)silane, cyclohexane-1,3-dione, 2-allylaminomethylene-5,5-dimethyl-, bis(2-ethylhexyl)phthalate (BEHP), etc. compounds were produced from the pyrolysis-catalytic steam reforming reaction. This sight is a crucial indication of utilizing microplastics pollution for value-added fuel production and decreasing the risk threats of marine life

Effect of combined Ce and Er Addition on Solidification, Microstructure of the Al-7Si-alloy

This paper highlights the effects of the additions of two rare earth elements (REEs) (Ce and Er) on microstructure and to investigate the characteristic temperatures during solidification of the modified alloy. Five changes of Al-7Si alloys with xEr+xCe additions (x=0.15, 0.25, 0.4, 0.5 and 0.75) were produced by casting technique via the solidification parameters examined using computer-aided cooling curve thermal analysis (CA-CCTA). The thermal analysis tests were carried out for each one by using a thermal analysis system that includes (K-type Thermocouple, EPAD-TH8-K, EPAD-Baes2 and Laptop with Dewesoft-7.5-Lt). To estimate the change in microstructure and solidification as a result of adding (Ce+Er) additions, the obtained result showed that the growth TG Al-Phase and nucleation TN Al-Phase temperatures decreased to lower temperatures 614.7°C and 615.5°C respectively as the amount Ce, Er increased

Strontium-doped chromium oxide for RhB reduction and antibacterial activity with evidence of molecular docking analysis

The emergence of multi-drug resistance (MDR) in aquatic pathogens and the presence of cationic dyes are the leading causes of water contamination on a global scale. In this context, nanotechnology holds immense promise for utilizing various nanomaterials with catalytic and antibacterial properties. This study aimed to evaluate the catalytic and bactericidal potential of undoped and Sr-doped Cr2O3 nanostructures (NSs) synthesized through the co-precipitation method. In addition, the morphological, optical, and structural properties of the resultant NSs were also examined. The optical bandgap energy of Cr2O3 has been substantially reduced by Sr doping, as confirmed through extracted values from absorption spectra recorded by UV-Vis studies. The field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) micrographs illustrate that the composition of Cr2O3 primarily consisted of agglomerated, irregularly shaped NSs with a morphology resembling nanoflakes. Moreover, the presence of Sr in the lattice of Cr2O3 increased the roughness of the resulting NSs. The catalytic activity of synthesized NSs was analyzed by their reduction ability of Rhodamine B (RhB) dye in the dark under different pH conditions. Their antibacterial activity was evaluated against MDR Escherichia coli (E. coli). Sr doping increased antibacterial efficiency against MDR E. coli, as indicated by inhibition zone measurements of 10.15 and 11.75 mm at low and high doses, respectively. Furthermore, a molecular docking analysis was conducted to determine the binding interaction pattern between NSs and active sites in the target cell protein. The findings corroborated antimicrobial test results indicating that Sr-Cr2O3 is the most effective inhibitor of FabH and DHFR enzymes

3D printing of a palladium-alumina cermet monolithic catalyst: catalytic evaluation in microwave-assisted cross-coupling reactions

A straightforward manufacture strategy is proposed to obtain an efficient and robust palladium-alumina (Pd0/Al2O3) cermet monolithic catalyst, specifically designed to perform safe microwave assisted organic synthesis (MAOS). In this approach, a cermet catalyst with high surface area, controlled composition and adapted shape and dimensions to a microwave reactor vessel is generated via 3D printing technology and sintering. The resulting catalyst has been explored in heterogeneous Suzuki, Sonogashira, Stille and Heck cross-coupling reactions, in MAOS. The Pd0 catalyst is permanently active, stable, without leaching and can be recycled and reused at least 200 reaction cycles. The generation of hot spots, sparking or hazardous discharges is controlled by the effective immobilization of the palladium in the monolithic structure during the reaction. The palladium content is forming part of both the internal and external structure, providing greater mechanical resistance and catalytic activity with respect to the basic ceramic material (alumina)This work was financially supported by the Consellería de Cultura, Educación e Ordenación Universitaria of the Galician Government: EM2014/022 to A.C., ED431B2016/028 to F.G. The Strategic Grouping AEMAT grant No. ED431E2018/08 and the Spanish Ministry of Science, Innovation and Universities with grant No: MAT2017-90100-C2-1-P "MA thanks Xunta de Galicia and the ERDF (ED431C 2021/21)"S

Valorization of lignocellulosic biomass into sustainable materials for adsorption and photocatalytic applications in water and air remediation

An exponential rise in global pollution and industrialization has led to significant economic and environmental problems due to the insufficient application of green technology for the chemical industry and energy production. Nowadays, the scientific and environmental/industrial communities push to apply new sustainable ways and/or materials for energy/environmental applications through the so-called circular (bio)economy. One of today’s hottest topics is primarily valorizing available lignocellulosic biomass wastes into valuable materials for energy or environmentally related applications. This review aims to discuss, from both the chemistry and mechanistic points of view, the recent finding reported on the valorization of biomass wastes into valuable carbon materials. The sorption mechanisms using carbon materials prepared from biomass wastes by emphasizing the relationship between the synthesis route or/and surface modification and the retention performance were discussed towards the removal of organic and heavy metal pollutants from water or air (NOx, CO2, VOCs, SO2, and Hg0). Photocatalytic nanoparticle–coated biomass-based carbon materials have proved to be successful composites for water remediation. The review discusses and simplifies the most raised interfacial, photonic, and physical mechanisms that might take place on the surface of these composites under light irradiation. Finally, the review examines the economic benefits and circular bioeconomy and the challenges of transferring this technology to more comprehensive applicationsOpen access funding provided by Universitat Rovira i Virgili. Authors are thankful for the support from Grant PID2021-123665OBI00 and TED2021-129343B-I00 funded by MCIN/AEI/ 10.13039/501100011033 and, as appropriate, by “ERDF A way of making Europe”, by the “European Union” or by the “European Union NextGenerationEU/PRTR”. Dr Ridha Djellabi acknowledges Maria Zambrano Grants-2021URV-MZ-1

Mesoporous alumina : A comprehensive review on synthesis strategies, structure, and applications as support for enhanced H2 generation via CO2-CH4 reforming

Lately, the generation of hydrogen out from carbon dioxide (CO2) - methane (CH4) reforming has been touted as a feasible option for reducing two of the most harmful greenhouse gases (CO2 and CH4) in the atmosphere. However, this technology typically suffered from catalyst deactivation triggered by sintering and coke deposition. Therefore, designing a feasible catalyst by making efficient support selections is vital for overcoming this challenge. Mesoporous alumina (MA) has aroused great attraction attributed to their potential applications as catalysis supports resulted from their high surface areas combined with tunable, narrow, and uniform pore size distribution, as well as their ability to constrain active metal from sintered and deactivated during the reaction. These materials' morphology, composition, and pore structure can be directly tailored during synthesis by altering the synthesis parameters like the type of the surfactants/templates employed, pH conditions, or selection of alumina precursors. As a result, this review's major focus is on synthesizing unique MA using a range of synthesis routes and conditions. Apart from that, this review also focuses on the applications and performance of MA as catalyst support during the CO2-CH4 reforming. We believe that this effort provides the complete grasp of MA contribution towards improving the CO2-CH4 reforming activity

Experimental and DFT study of GO-decorated CaO quantum dots for catalytic dye degradation and bactericidal potential

This research lays the groundwork for preparing graphene oxide (GO)-doped CaO nanocomposites for efficient antibacterial potential and dye degradation. The study aimed to reduce the recombination rate of the electron hole (e−/h+) of CaO and improve charge transfer. This issue can be minimized by doping high-surface area GO into CaO quantum dots (QDs). Herein, the one-pot co-precipitation technique has prepared various concentrations (1, 3, and 5 wt%) of GO-doped CaO. Characterization techniques were used to investigate optical, elemental analysis, microstructural, functional, and morphological properties. The addition of GO into QDs showed excellent catalytic activity (CA) to control sample CaO against methylene blue (MB) in basic and acidic media compared to the neutral media. The synergistic effect of morphological alternation attributed to an increase in the mechanism of CA upon doping. Various concentrations of GO to QDs promised remarkable bactericidal potency against Escherichia coli

Peptide-Based Vaccine against Breast Cancer: Recent Advances and Prospects

Breast cancer is considered the second-leading cancer after lung cancer and is the most prevalent cancer among women globally. Currently, cancer immunotherapy via vaccine has gained great attention due to specific and targeted immune cell activity that creates a potent immune response, thus providing long-lasting protection against the disease. Despite peptides being very susceptible to enzymatic degradation and poor immunogenicity, they can be easily customized with selected epitopes to induce a specific immune response and particulate with carriers to improve their delivery and thus overcome their weaknesses. With advances in nanotechnology, the peptide-based vaccine could incorporate other components, thereby modulating the immune system response against breast cancer. Considering that peptide-based vaccines seem to show remarkably promising outcomes against cancer, this review focuses on and provides a specific view of peptide-based vaccines used against breast cancer. Here, we discuss the benefits associated with a peptide-based vaccine, which can be a mainstay in the prevention and recurrence of breast cancer. Additionally, we also report the results of recent trials as well as plausible prospects for nanotechnology against breast cancer