The Effects of Ce and W Promoters on the Performance of Alumina-Supported Nickel Catalysts in CO2 Methanation Reaction

The influence of Ce and W promoters on the performance of alumina-supported nickel catalysts in the CO2 methanation reaction was investigated. The catalysts were obtained by the co-impregnation method. Nitrogen low-temperature adsorption, temperature-programmed reduction, hydrogen desorption, transmission electron microscopy, X-ray diffraction, and photoelectron spectroscopy studies were used for catalyst characterization. An introduction of Ce and W promoters (1–5 wt %) led to the decrease in mean Ni crystallite size. Gradual increase in the active surface area was observed only for Ce-promoted catalysts. The increase in CO2 conversion in methanation reaction at low-reaction temperatures carried out over Ce-promoted catalysts was attributed to the increase in the active surface area and changes in the redox properties. The introduction of small amounts of tungsten led to an increase in the activity of catalysts, although a decrease in the active surface area was observed. Quasi in situ XPS studies revealed changes in the oxidation state of tungsten under CO2 methanation reaction conditions, indicating the participation of redox promoter changes in the course of surface reactions, leading to an improvement in the activity of the catalyst.

Optimization of Operating Conditions for CO2 Methanation Process Using Design of Experiments

In this study, the Taguchi experimental design method using an L16 orthogonal array was attempted in order to investigate the optimal operating conditions for the CO2 methanation process in Ni-based catalysts. The relative influence of the main factors affecting CO2 conversion and CH4 yield was ranked as follows: reactor pressure > space velocity > reaction temperature. The optimal combination of operating conditions was a reactor temperature of 315 °C, a pressure of 19 bar, and a space velocity of 6000 h−1. The effect of the H2/CO2 ratio on CO2 conversion and CH4 yield was further considered under these optimal operating conditions. Moreover, the catalyst was characterized in order to investigate the production of coke through Brunauer–Emmett–Teller analysis, thermogravimetric analysis, and scanning electron microscopy. The amount of coke produced after the reaction for approximately 24 h was ~2 wt.%. Therefore, the desired CH4 yield and long-term operational stability were successfully obtained using the Taguchi design method and catalyst characterization.

Hydrogenation of coconut oil into Biofuel (bio-jet fuel and high-value low molecule hydrocarbons)

The performance of Ni/HZSM-5, HZSM-5, and without a catalyst have been investigated for the hydrogen pressure range of 10-40bar hydrocracking of coconut oil in a packed-bed tubular reactor between 300-450°C. This study concentrates on the effect of the operating parameters (reaction pressure, type of catalyst and reaction temperature) on the yield of transportation fuel carbon range (C5-C22) using the One-Variable-At-A-Time approach. The objectives of this study are to evaluate the effect of process conditions which includes: temperature, pressure, and presence of a catalyst, and to compare the activity of Ni/HZSM-5, HZSM-5 and without catalysts. All tested catalysts were effective in attaining biofuel range in the liquid product. The highest yield and performance of gasoline liquid composition 83.03% was obtained from the reaction pressure at constant temperature of 450 ͦC in 40bar where HZSM-5 catalysts was used, the yield of gasoline liquid composition 82.25% was also produced at constant pressure of 40 bar in 300 ͦC where promoted catalyst(Ni/HZSM-5) was used. Hydrocracking coconut oil under Ni/HZSM-5 catalysts produced the highest yield of jet fuel liquid compositions 78.73% at constant temperature 300°C, and pressure of 10 bar, this was due to less coke that was formed within a reactor and less temperature of 300°C. The highest yield of jet fuel liquid composition 75.67% was also produced at constant pressure of 10 bar at muximum temperature of 450 ͦ C, this was also due to less coke that was formed within a reactor where HZSM-5 was used because of less pressure applied. For the highest yield of diesel liquid composition 24.04%, constant temperature at 400 ͦC of 20 bar where Ni/HZSM-5 was used in figure:5-9 and the highest yield of diesel liquid composition 25.15% was also produced at constant pressure of 20 bar in 450 ͦC where HZSM-5 was used. X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) coupled with Energy- dispersive X-ray spectroscopy (EDS) analyses were employed for catalyst characterization. XRD patterns confirm the success of metal doping on ZSM-5. Major peaks at 9.1° and 22.9° corresponding to ZSM-5 crystals were observed in ZSM-5. Impregnation with metals reduced the crystallinity of ZSM-5 supported catalysts.

A Green Synthesis Strategy of Binuclear Catalyst for the C-C Cross-Coupling Reactions in the Aqueous Medium: Hiyama and Suzuki–Miyaura Reactions as Case Studies

Cellulose, as a green and available phytochemical, was immobilized on the surface of magnetite nanoparticles then doped with imidazole and Co. complex (Fe3O4@CNF ∼ ImSBL ∼ Co.) and used as a water-dispersible, recyclable and efficient nano catalyst for the synthesis of C−C cross-coupling reactions including fluoride-free Hiyama and Suzuki reactions in an aqueous medium as an efficient and vital solvent, due to their high application and importance in various fields of science. Different spectroscopic and microscopic techniques were used for the catalyst characterization such XRD, FESEM, TEM, FT-IR, EDX, DLS, VSM, UV-Vis, and ICP analyses. The presence of imidazole as ionic section tags with hydrophilic character on the Co-complex supported on magnetic nanoparticles provides dispersion of the catalyst particles in water, which leads to both higher catalytic performance and also facile catalyst recovery and reuse six times by successive extraction and final magnetic separation. High catalytic activity was found for the catalyst and high to excellent efficiency was obtained for all Suzuki (80–98% yield; E factor: 1.1–1.9) and Hiyama (87–98% yield; E factor: 0.26–1.1) derivatives in short reaction times under mild reaction conditions in the absence of any hazardous or expensive materials. There is not any noticeable by-product found whether for Suzuki or Hiyama derivatives, which reflects the high selectivity and also the lower the E factor the more favorable is the process in view of green chemistry. The bi-aryls were achieved from the reaction of various aryl iodides/bromides and even chlorides as the highly challenging substrates, which are more available and cheaper, with triethoxyphenylsilane or phenylboronic acid. To prove the performance of the catalyst components (synergistic of SBL ∼ Co. and IL), its different homologs were incorporated individually and studied for a model reaction. Exclusively, this is an introductory statement on the use of Cobalt binuclear symmetric ionic liquid catalysts in Hiyama reactions.

Development of a Novel Microgap Reactor System for the Photocatalytic Degradation of Micropollutants from Aqueous Solutions with TiO2-Based Photocatalysts Immobilized by Spray Coating

The presented investigation focuses on the development of a novel microgap reactor concept for the photocatalytic degradation of micropollutants from aqueous solutions with titanium dioxide-based catalysts immobilized by spray coating. Combinatorial experiment designs were utilized in order to study the influence of the microgap width, irradiance and catalyst layer thickness on the conversion of 17 α-ethinyl estradiol. The impact of catalyst-doping is discussed as well. Regarding conversion analyses, LC-MS/MS and GC-MS techniques were deployed, while XRD, ESEM and BET were utilized for catalyst characterization. The results show that the built-up microgap reactor system enables a conversion of 65% within a residence time of 2.7 min with UV-A irradiation and under steady flow conditions. Thus, the presented bench scale photocatalysis reactor provides promising fundamental findings for the future development of pilot scale approaches. With the deployment of industrial catalysts and base materials, microgap reactor photocatalytic degradation represents an attractive technology for large-scale application.

Insights into the Kinetics Degradation of Bisphenol A by Catalytic Wet Air Oxidation with Metals Supported onto Carbon Nanospheres

Emerging pollutants are an increasing problem in wastewater globally. Bisphenol A (BPA) is one compound belonging to this group. This work proposes the study of the employment of several metal-supported (2 wt. %) carbon nanospheres (CNS) for BPA degradation by catalytic wet-air oxidation. Several techniques were used for the catalyst characterization: thermogravimetry, X-ray diffractometry (XRD), Fourier transformed infrared spectrometry (FTIR), determination of isoelectric point, elemental analysis, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and N2 adsorption–desorption isotherms. Different loads of Ru in the catalyst were also tested for BPA degradation (1, 2, 5, 7, and 10%), being the first minimum value to achieve a conversion above 97% in 90 min 2 wt. % of Ru in the CNS-Ru catalyst. In the stability test with CNS-Ru and CNS-Pt, CNS-Pt demonstrated less activity and stability. Two potential models were proposed to adjust experimental data with CNS-Ru(2%) at different conditions of BPA initial concentration, catalyst mass, temperature, and pressure of the reaction. Both models showed a high determination coefficient (R2 > 0.98). Finally, the efficiency of CNS-Ru and CNS-Pt was tested in a real hospital wastewater matrix obtaining better results the CNS-Pt(2%) catalyst.

Microwave assisted synthesis of benzimidazole derivatives using tetra butyl ammonium chloride as phase transfer catalyst, characterization, biological activities and molecular docking studies

Benzimidazole and its derivatives are of wide interest because of their diverse biological activity and clinical applications. The heterocyclic imidazole core is a common moiety in a large number of natural products and pharmacologically active compounds and because of that they are possessing inhibitory activity as well as favorable selectivity ratio. Benzimidazoles exhibit significant activities like anti-microbial, anti-viral, anti-diabetic, anti-cancer activity, numerous antioxidants, anti-parasitic, anti-helmintics, antiproliferative, anti-HIV, anti-convulsant, antiinflammatory, anti-hypertensive, anti-neoplastic, proton pump inhibitor and anti-trichinellosis. The synthesis of benzimidazole derivatives remains a focus of medicinal research. Here benzimidazole derivatives were synthesized using two phase system under microwave conditions using the phase transfer catalyst tetra butyl ammonium chloride (10% mol) in good yield. The molecular docking study against 4GQQ protein with synthesized benzimidazole derivatives was performed to see the necessary interactions responsible for anti-bacterial activity.

Exploiting In-Situ Characterization for a Sabatier Reaction to Reveal Catalytic Details

In situ characterization of catalysts provides important information on the catalyst and the understanding of its activity and selectivity for a specific reaction. TPX techniques for catalyst characterization reveal the role of the support on the stabilization and dispersion of the active sites. However, these can be altered at high temperature since sintering of active species can occur as well as possible carbon deposition through the Bosch reaction, which hinders the active species and deactivates the catalyst. In situ characterization of the spent catalyst, however, may expose the causes for catalyst deactivation. For example, a simple TPO analysis on the spent catalyst may produce CO and CO2 via a reaction with O2 at high temperature and this is a strong indication that deactivation may be due to the deposition of carbon during the Sabatier reaction. Other TPX techniques such as TPR and pulse chemisorption are also valuable techniques when they are applied in situ to the fresh catalyst and then to the catalyst upon deactivation.