At this moment the major challenge for the human beings is to address uninterrupted raise in CO2 emissions and their consequences. The demands of globalization don’t permit to minimize the CO2 emissions. The possible options to address issues related CO2 emissions are (a) Use of renewable energy sources (b) CO2 capture and storage (CCS) (c) CO2 capture and utilization (CCU). However, the utilization of CO2 in the production of chemicals is eco-economically advantageous. The utilization of CO2 involves the conversion of CO2 or use of CO2 as co-feed in the reaction streams. The research community is progressive to develop CO2 conversion technologies at various levels. The present review focuses on the recent trends in emission and utilization of CO2 as feed stock for catalytic production of organic carbonates which possess ample industrial applications and use of CO2 as soft oxidant in catalytic oxidative dehydrogenation reactions of hydrocarbons. Various catalytic systems for both the conversions are discussed.Graphical AbstractThe approach towards CO2 emissions is changing from CO2 Capture and Storage (CCS) to CO2 Capture and Utilization (CCU). The present review focused on the utilization of CO2 as feed stock in dehydrogenation reactions and synthesis of organic carbonates using variety of catalysts.

The adsorption properties for some gas molecules (H2, N2, CO, NO and CO2) on pristine and transition metal-doped h-BN monolayer are investigated by using density functional theory (DFT) calculations. In contrast with N vacancy (VN) substrates, those with B vacancy (VB) are more easily doped with metal atoms, among which Ti atom doping shows the lowest binding energy. For the adsorption of these gas molecules, NO is most easily adsorbed on h-BN monolayer with metal dopants, especially Pt doped system yields the lowest adsorption energy of NO. Since a NO molecule on Pt doped h-BN monolayer could not be directly decomposed into Oads and Nads due to the high reaction energy barrier (≈ 2.00 eV), the (NO)2 dimmer can interact with Pt to form a five-membered ring or a four-membered ring through two different Langmuir–Hinshelwood (LH) mechanisms for NO reduction catalytic reaction, respectively. The LH1 reaction process needs to overcome relatively lower energy barriers, while the product of the LH2 mechanism has a more stable structure. For the catalytic process of CO oxidation, the remained Oads can bind with CO and form CO2, by overcoming a much lower energy barrier of only 0.14 eV. It seems that Pt doping can enhance the adsorb capacity of h-BN monolayer for the gas molecules and the potential catalytic activity for electrochemical reduction of NO.

In this work, comparative testing of the activity of low-percentage palladium and palladium-nickel catalysts supported on activated diatomite with a commercial nickel catalyst from BASF was carried out in the process of hydrogenation of polyalphaolefins (PAO-4). It has been found that palladium catalysts carry out the process under milder conditions, demonstrate higher activity compared to nickel catalysts, significantly reduce the process time, and provide a higher degree of hydrogenation. The activity of bimetallic catalysts is lower than that of monometallic palladium catalysts. Furthermore, Ni exhibits a reaction temperature of at least 150 °C, while Pd is at least 110 °C. If nickel is a single-use catalyst, then when palladium is used 5 times remains an excellent catalytic activity. Catalyst activity is related to the form of adsorbed hydrogen, and on Pd catalyst hydrogen is weakly bound form, while on Ni hydrogen is strongly bound form. The physicochemical characteristics of catalysts and polyalphaolefin oils also have been determined.

The production of aromatics with fuel properties from either biomass resources or low-cost refinery streams such as C5 is an important industrial interest. However, the strategic design of reliable catalysts with commercial compatibilities remained a challenge. Several investigations were carried out in this direction. This review accordingly presents a comprehensive analysis of the literature on the catalysis-based strategies adopted for aromatization of the feeds. Valorization of furans and allied oxygenates derived from biomass into aromatics was initially covered. The review examined strategies for C5 streams aromatization, co-upgrading of furans with hydrocarbons and methanol and discussed how biomass-derived bio-oils could be valorized into aromatics. In addition to discussion on the influence of catalytic textural, acidity and topological properties, the paper provided substantial updates on the associated reaction mechanisms. A perspective for further investigations in aromatization was also provided.

Although nanostructures based on noble metal alloys are widely used in the anode catalysts of direct ethanol fuel cells, their commercialization remains a remarkable challenge due to their high cost and poor durability. We describe the successful synthesis of trimetallic PtTiMg alloy nanoparticles with adjustable composition using a simple one-step three-target magnetron co-sputtering method. Various physical characterization and electrochemical methods were used to investigate the structure/composition and electrochemical properties of the obtained PtTiMg alloy catalysts toward ethanol oxidation reaction (EOR). The PtTiMg alloy catalyst demonstrated excellent electrocatalytic activity and high durability when the Mg content was 2.76%, (after 3000 cycles, retained 91% of its electrochemical surface area). Furthermore, the electrochemically active surface area and peak current density of the PtTiMg alloy catalyst are 1.5 and 0.8 times higher than those of the commercial pure Pt catalyst, respectively. Furthermore, the long-term strong acid immersion test demonstrated that the PtTiMg alloy catalysts retain high electrocatalytic activity in harsh environments, demonstrating the potential application of the obtained PtTiMg alloy catalysts for EOR.

The catalytic performances and mechanism differences of model catalysts Cu–SSZ-13 and Fe–SSZ-13 with similar metal content and Si/Al ratio were compared. In the NH3-SCR reaction, Cu–SSZ-13 had a good NO conversion at low temperature, broad active temperature windows and better hydrothermal stability. Fe–SSZ-13 showed better high-temperature NO conversion rate and better resistance to sulfur poisoning, but poorer low-temperature NH3-SCR activity. NH3-TPD verified the content difference of L-NH3 and B-NH3 of Cu- and Fe–SSZ-13. UV–Vis DRS, EPR, H2-TPR indicated the active species of Cu- and Fe–SSZ-13. Results showed that Cu–SSZ-13 only had one type active species of Cu2+, Fe–SSZ-13 had Fe3+ species that acted as active centers at low temperature and reactivity oligomeric Fe species at high temperature. The diffuse reflection infrared Fourier transform spectrum (DRIFTS) results showed that the reactions of Cu–SSZ-13 and Fe–SSZ-13 at low temperature both followed the Eley–Rideal (E–R) mechanism and the Langmuir–Hinshelwood (L–H) mechanism. Cu–SSZ-13 could perform the catalytic process well under both mechanisms, but when Fe–SSZ-13 followed the E–R mechanism, there were many B-NH3 species, which was not conducive to the reaction. When following the L–H mechanism, the speed of NO3− participating in the reaction was slow due to ammonia inhibition, resulting in poor low-temperature activity.

An acid gas stream was utilized instead of pure H2S as feedstock in the methanol thiolation reaction with Alkali/W/γ-Al2O3 catalysts. The catalysts were synthesized through incipient wetness impregnation and characterized by XRD, BET, and NH3-TPD methods. The catalytic tests were performed in a fixed-bed flow reactor for an acid gas with 12.2%mol. H2S at atmospheric pressure, 360 °C, H2S to methanol molar ratio of 2, and LHSV of 0.5 h−1. The results were then compared with the case in which pure H2S was used as feedstock. H2S conversion was lower in the acid gas feed than in pure H2S feed due to participation of catalysts in hydrocarbon reforming reactions. Cesium-promoted catalysts gave the best results. H2S in acid gas was converted about 92.8%. The yields were reported about 87.3% and 5.5% for dimethyl sulfide and methanethiol as organosulfur products respectively. The amount of hydrogen increased by about 110% in the reactor outlet.

Nitrogen-doped carbon with and without Fe additives is a promising alternative for commercial Pt/C catalysts for the oxygen reduction reaction (ORR) in proton and anion exchange membrane fuel cells. To understand the nature of the rate-determining steps (RDSs) of the ORR over newly developed catalysts, the analysis of the Tafel slopes of ORR voltammograms is beneficial for elucidating the number of electrons involved in the RDS. Conventionally, the Tafel slope is evaluated from the measured total current, which involves several different reaction pathways: the four-electron pathway from O2 to H2O described with a kinetic constant k1, the two-electron pathway from O2 to H2O2 with k2, and the two-electron pathway from H2O2 to H2O with k3. This method provides reasonable Tafel slopes as long as the measured ORR is selective to a particular reaction pathway, such as the four-electron pathway over a Pt/C catalyst; however, typical Fe/N/C and N/C catalysts have mixed reaction pathways and analyzing the Tafel slopes from the total current does not provide meaningful information. To address this, we propose a new methodology for analyzing Tafel slopes. In this study, the measured ORR currents were converted into inherent kinetic constants (k10, k20, and k30) using the Nabae model, which was previously developed by our group, and the Tafel plots for k10, k20, and k30 were analyzed to determine the Tafel slopes of each reaction pathway. Four ORR systems (Fe/N/C and N/C catalysts in acid and base) were analyzed using the proposed method, and the differences in the reaction mechanisms were successfully reflected in the determined parameters.

Herein, we report the anchoring of a bis(oxime palladacycle) adduct on magnetic mesoporous silica (Fe3O4@SBA-15). Magnetic mesoporous silica was successively treated with (3-aminopropyl) triethoxysilane (APTES), cyanuric chloride (CC), and 4-hydroxyacetophenone oxime-derived palladacycle to give Fe3O4@SBA-AP-CC-bis(oxime palladacycle). The obtained nano-catalyst was characterized by FT-IR spectroscopy, CP MAS 13C NMR spectroscopy, scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), Brunauer–Emmett–Teller surface area measurement (SBET) and X-ray diffraction spectroscopy (XRD). X‐Ray photoelectron spectroscopy (XPS) corroborated the (+ 2) oxidation number for palladium. The catalytic potential of Fe3O4@SBA-AP-CC-bis(oxime palladacycle) was explored in the Mizoroki–Heck reaction. The effects of different reaction conditions, including the solvent, the base, temperature, and palladium content, were studied in detail. The N-methylpyrrolidone (NMP) solvent, 0.5 mol% of the Pd-catalyst, the NaOAc base, and the reaction temperature of 120 °C, provided the best conditions for the Heck cross-coupling reaction. The catalyst showed a wide substrate scope, including aryl halides (I, Br, Cl) and olefins, in the Mizoroki–Heck reaction, using low catalyst loadings viz., Pd 0.09 mol%. The bis(oxime palladacycle) enjoys easy magnetic separation, stability, and recyclability over five runs.

Light naphtha (C5–C6 alkanes) is commonly used as a feedstock for steam cracking or catalytic cracking to produce ethylene and propylene. This paper summarizes the progress of C5/C6 alkanes steam cracking and catalytic cracking, but the key problem of the above method is the high yield of low-value C1–C3 alkanes. When C5/C6 olefin is used as the feedstock of catalytic cracking, the ethylene and propylene yields are high, while the C1–C3 alkanes yield is low. It is of scientific value to dehydrogenate the C5/C6 alkanes into the corresponding olefins, and effectively convert the olefins into ethylene and propylene. This paper reviews recent progress of direct catalytic dehydrogenation and oxidative dehydrogenation of C5/C6 alkanes, and points out that the key is to develop C5/C6 alkanes dehydrogenation catalyst for selective preparation of corresponding mono-olefins. The main issues about how to develop highly selective C5/C6 alkanes dehydrogenation catalysts are proposed.

Traditional catalysts with one core and one shell structure have few active sites and shell structure parameters are difficult to be regulated. In order to solve these two problems, it is presented herein a multi-Pd-core and porous carbon shell catalyst mPd@HCS, where multiple Pd nuclei provide more active sites for the reaction, the shell structure parameters are tuned by the adjustment of shell thickness, and the influence of shell thickness on the performance of H2O2 direct synthesis was mainly investigated. The results showed that the selectivity and yield of H2O2 changed volcanically with the increase of carbon crust thickness because of the compromise between reactants diffusion and product degradation, and the selectivity (87%) and productivity (1938 mmol gPd−1 h−1) of the sample with middle shell thickness (10.18 nm) were the highest.

New organic-inorganic mesoporous hybrid materials containing terbium complexes covalently attached to mesoporous silica SBA-15 have been successfully prepared. The mesoporous silica SBA-15 was modified with 3,4,5-tri hydroxyphenyl acetic acid ligand and then used to fabricate the lanthanide-based mesoporous material SBA-15@3,4,5-tri hydroxyphenyl acetic@ Tb. The mesoporous material was characterized by Fourier transforms infrared (FTIR) spectra, powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results show that the 3,4,5-tri hydroxyphenyl acetic acid ligand and Tb ions are attached to the SBA-15 host. The catalysts were tested in the synthesis of 5-substituted 1H-tetrazoles. This catalyst is an efficient catalyst for [3 + 2] cycloaddition with NaN3 to prepare 5-substituted 1H-tetrazoles. The catalyst was recycled for up to six cycles without significant loss of activity.

CO2 (dry) reforming of methane (DRM) is a significant and useful reaction from the standpoint of effective utilization and conversion of two main greenhouse gases to value-added synthesis gas. To achieve highly efficient and stable DRM reaction, a Silicalite-1-encapsulated ultrafine Ni nanoparticle catalyst (Ni@S-1)by using Ni phyllosilicate (Ni-PS) as precursor was newly developed. This Ni@S-1 catalyst exhibited negligible coke deposition (0.5 wt.%) evaluated at 600 °C for 5 h. Additionally, this Ni@S-1 catalyst presented high and stable catalytic performances and maintained the Ni nanoparticles with ultrafine size (< 7 nm) at 850 °C for 24 h. Therefore, this Ni@S-1 catalyst showed good suppression of coke formation and high resistance to nickel sintering and thus was promising for DRM reaction.

Fluidized Catalytic Cracking (FCC) is one of the key processes of any petroleum refinery as it produces gasoline, Liquefied Petroleum Gas (LPG) and valuable petrochemical feedstock viz. ethylene and propylene. FCC is a catalytic process where zeolite (USY and ZSM-5) based catalysts are being used, contain a high concentration of acidic sites, which are responsible for cracking heavy hydrocarbon molecules into smaller ones. During these cracking reactions, significant coke formation occurs over the catalyst surface and blocks the pores, thus resulting drop in catalytic activity. To regain the catalyst activity, the coke on the catalyst is burned in the FCC regenerator unit and provides heat demand for the FCC riser bed where the cracking reaction takes place and the cycle continues. The temperature of the FCC regenerator reaches around 700 °C due to the combustion of coke on the catalyst. Due to incomplete combustion of coke on catalyst produces CO which burns above the catalyst bed, which is denoted as a dilute bed. The heat of reaction of CO combustion needs to be realized on catalysts bed and also to avoid the heat loss in the regenerator dilute bed. Higher dilute bed temperature damages the FCC regenerator internals, which is to be avoided. Conventionally, additives named CO Combustion Promoters (COPs) have been used for the promotion of CO to CO2 in the catalyst bed which helps in improving regeneration of FCC equilibrium catalysts. The present article covers the concept and various types of COP reported in the literature. Different preparation methodologies, physico-chemical properties and evaluation results have been discussed. These insights would be helpful to understand the structure–property–activity relationship of COP. Further, it can also help to select the right COP for the desired commercial applications.

The over-consumption of petroleum fuel due to the progressive increase in population, transportation, industrialization, modernization as well as improvement in the lifestyle of the society leads to the fast declining of non-renewable resources. Therefore, it is important to discover low cost, environmentally friendly and sustainable surrogates of petroleum fuels. In this regard, biodiesel production is one of the gorgeous solutions for the research community. Contrary to the benefits, the high cost of the biodiesel is the main disadvantage, greatly reliant on the feedstock. In this sense, wild olive oil was explored for the first time as a suitable and novel feedstock for biodiesel technology development. The fatty acid composition was identified by GC–MS analysis whereas various physiochemical properties were determined by ASTM and EN methods. Furthermore, this review paper conveys a detailed overview of biodiesel production technologies, various generation feedstocks and types of catalyst along with their plausible mechanism.

Nanostructured powders xFe/nano-Al2O3 with the Fe loading of x = 0.0 – 5.0 wt% were obtained using laser vaporization by CO2 laser. XRF, XRD, HRTEM, PL and UV–Vis DRS techniques were employed to investigate physicochemical, structural and optical properties of the synthesized nanopowders with the average particle size of 9 nm. Nanopowders xFe/nano-Al2O3 as model catalysts were tested in isobutane dehydrogenation reaction. The results obtained were compared with similar data for the xFe/γPb-Al2O3 systems synthesized by the conventional sol–gel method. According to XRD and UV–Vis DRS data, in the series of xFe/nano-Al2O3 samples a great part of Fe3+ ions is in the disordered environment of subsurface layers of Al2O3 nanocrystallites, predominantly in the tetrahedral coordination. In distinction to samples of the xFe/γPb-Al2O3 series, in the case of nanostructured xFe/nano-Al2O3 powders the formation of Fe2O3 phase does not occur at any concentrations of iron or conditions of testing. The analysis of the PL spectra of xFe/nano-Al2O3 powders also showed the presence of surface sites of Fe3+ ions, which were not detected for xFe/γPb-Al2O3. Catalytic testing of the xFe/nano-Al2O3 series samples in isobutane dehydrogenation revealed the formation of the iron active sites that ensure catalytic activity of the samples. Differences in the catalytic properties of FeOx/Al2O3 samples obtained by the sol–gel method and laser vaporization are related to different states of Fe3+ ions. Thus, the xFe/nano-Al2O3 nanopowders, in contrast to xFe/γPb-Al2O3, contain a large amount of active Fe3+ sites. These sites, being involved in the dehydrogenation reaction, are present predominantly on the surface of the nanopowders.

In this work, we report for the first time, the tungstic acid-catalyzed oxidation of terpene alcohols with hydrogen peroxide. This simple, solid, and commercially available catalyst efficiently promoted the conversion of borneol, geraniol and nerol to camphor and epoxide products, respectively. Effects of main reaction parameters, such as catalyst load, the molar ratio of oxidant to the substrate, time, and reaction temperature were investigated. Conversions and selectivity greater than 90% were achieved using 1.0 mol % of H2WO4 after 2 h of reaction at 90 °C. The activation energy was equal to 66 kJmol−1. We propose a reaction mechanism based on the experimental results. This solid catalyst was easily recovered and reused without loss of activity. As far as we know, it is the first time that tungstic acid was used as the catalyst in the oxidation reactions of terpene alcohols.Graphical Abstract

The present study focused on the modification of zeolite H-BEA via a desilication post-synthetic approach in the presence of a cationic surfactant, dodecyltrimethyl ammonium bromide (DTAB), to synthesise a micro-meso composite of zeolite BEA (mesozeolite BEA). Several techniques were used to characterise the modified zeolite H-BEA catalyst, including scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS-NMR), high and low angle X-ray diffraction (XRD), Fourier transformed infrared (FT-IR) spectroscopy, N2 sorption isotherms analysis etc. The synthesised mesozeolite exhibited bimodal porosity (micro and meso) and enhanced catalytic characteristics (surface area, acidity, and thermal strength) as compared to the parent zeolite H-BEA. The catalytic potential of the micro-meso H-BEA catalyst was investigated in the esterification of levulinic acid (LA) to n-butyl levulinate. The Box-Behnken Design (BBD) approach was used to optimise the process parameters for the catalytic reaction. Analysis of variance (ANOVA) was implemented to examine the appropriateness and importance of the quadratic model. The synthesised mesozeolite was found to be a highly efficient catalyst under the optimized reaction conditions, with 99.2% LA conversion, 97% yield, and 97% selectivity of n-butyl levulinate.Graphical AbstractMesozeolite H-BEA catalyzed synthesis of n-butyl levulinate, a value-added chemical

Solid acid catalysts of MgO–Al2O3 mixed oxides containing B4O72−, HPO42−, Mo7O246−, MoO42−, WO42−, and SO42− were synthesized by anion exchange with Cl− located in the space between anionic layers of hydrotalcite, followed by heat treatment at 773 K. The distance between the hydroxide layers was expanded by the intercalation of oxyanions larger than Cl−. The exchange of oxyanions in the interlayer space was confirmed by IR spectroscopy. Acid sites were generated on the obtained mixed oxides of MgO–Al2O3 by the electron withdrawing effect of the oxyanions. The acid catalyzed ethanol dehydration into ethylene and diethyl ether took place on the obtained catalysts. The effect of exchanged anions in the generation of acid sites was the largest in SO42−.

A combination of two base-metal oxides in tandem configuration can realize three-way reaction without platinum group metals. For this purpose, catalysts for hydrocarbon preferential oxidation (HC-PROX) and for NO reduction by CO are required. For the design of HC-PROX catalysts, competitive oxidation of propene and CO on spinel-type MFe2O4 (M = Co, Cu, Mg, Mn, Ni, Zn) was investigated. MnFe2O4 preferentially oxidized propene in the co-presence of CO showing the best propene oxidation activity. Among the series of MFe2O4, the activity controlling factor was correlated to the M-O bond energy of the second metal oxides, and the preference for HC oxidation was dependent on the electronegativity of the second ion. A tandem catalyst using MnFe2O4 for HC-PROX and CuCo2O4 for NO-CO reaction showed TWC activity comparable to a Rh/CeO2.