The [Fe, Al]-FER zeolites, which are prepared from the interzeolite conversion method (from MWW to FER topology) with high Al and Fe content (Si/Al of 8–18 and Si/Fe of 11–13), exhibit excellent catalytic performances and hydrothermal tolerance for NH3-SCR reaction. The interzeolite conversion process can be tuned by optimizing the zeolite synthesis conditions such as synthesis gel composition, crystallization time, crystallization temperature, and adding MWW seeds. The work can provide a new strategy to synthesize high Al and Fe content zeolite with high hydrothermal stability for NOx removal.

Bimetallic Ni-Cu catalysts supported on halloysite nanotubes with different metal contents (Hal-Ni80Cu20, Hal-Ni70Cu30, Hal-Ni42Cu58) were prepared and employed in the catalytic degradation of chitosan (CS). The relationship between catalytic performances of the catalysts with the different metal contents were studied. The highest catalytic activity was reported for Hal-Ni42Cu58 due to the higher proportion of the active Cu2+ in the catalytic degradation. Furthermore in Hal-Ni42Cu58, CuO persisted dominantly with Ni(OH)2 as compared to Hal-Ni80Cu20 where Cu(OH)2 was also available. Overall, the bimetallic-supported Hal catalysts displayed better catalytic activities than monometallic supported catalysts due to the synergistic effect between the metals.

Novel Ni2+-doped NixMg0.5Zn0.5-xFe2O4 [x = 0.0 to 0.5] nano-ferrites have been successfully prepared by the facile co-precipitation method. The XRD data demonstrated the formation of a single-phase cubic spinel structure. The optical band gap of the synthesized samples was found to increase with increasing Ni2+ content from 1.72 eV (x = 0.1) to 1.82 eV (x = 0.5). Samples with Ni2+ doping exhibit a transition from superparamagnetic to soft ferromagnetic activity. Ni0.5Mg0.5Fe2O4 catalyst has been found to have enhanced degrading efficiencies of 95.92 and 90.21% against methylene blue and xylenol orange in visible light, respectively. The main reactive species, as determined by scavenging activity, were hydroxyl radicals.

High-energy facets exposed nanotubular alumina as well as conventional alumina supported Pd catalysts were synthesized and applied to the selective hydrogenation of phenylacetylene. Novel alumina supported catalyst presented higher selectivity at complete conversion of phenylacetylene. This could be related to the well dispersion of Pd and strong metal-support interaction, which are the consequences of the unique structural properties of the crystal plane regulated alumina. It helps create more active sites for hydrogenation meanwhile facilitates the desorption of alkene and thus suppresses the excess hydrogenation towards ethylbenzene.

Nonthermal plasma-assisted reactions at ambient temperature hold promise for applications in upcycling of polymer wastes. Transient studies showed that the H2 response led that of D2, indicating that CH breaking occurred earlier than D-OD bond breaking in D2O-rubber and D2O-CO2-rubber reactions. The CH4 response led that of C2H6, indicating that Ni-based catalyst is highly favorable for catalyzing the formation of CH4. CO2 plasma produced oxygen which could oxidize part of CH4 and C2H6 from rubber. This study demonstrated that the transient kinetic (response) method, for the first time, is effective in producing data for elucidating mechanisms of nonthermal plasma-assisted catalysis.

Catalytic methane combustion was carried out over YSZ, Pd/YSZ and Rh/YSZ between 200 and 700 °C. Despite similar light-off curves for Pd/YSZ and Rh/YSZ between 200 and 450 °C, isotopic exchange experiments using CD4 and 18O2 revealed different behaviour of both supported catalysts regarding the activation of reactant molecules. The use of C18O2 isotopic gas was shown to be more appropriate than 18O2 to evaluate the bulk oxygen mobility in YSZ at low temperatures. The exchange of gaseous CO2 with lattice YSZ oxygen atoms, which occurs via surface hydrogen carbonate intermediate species, allowed to demonstrate the contribution of bulk oxygen atoms of YSZ in Rh/YSZ at low temperatures.

Nowadays, fertilizers are used to boost crop production. Nitrogenous fertilizers are assimilated as nitrate. Unfortunately, 60–70% of nitrogen is lost due to different leaching processes. Photocatalytic urea oxidation is now emerging as a new methodology. Nitrate conversion is favorable under alkaline pH. However, it can subsequently cause deprotonation of ammonium ions to result ammonia leaching. In this report, efficiencies of bare and RGO loaded TiO2 were examined. In the presence of NaF, the nanocomposite possesses a 9.8(1)% nitrate yield, significantly greater than the other analogous reactions. Such observation will be helpful in developing new methodologies to afford sustainable agriculture.

The design of catalysts active for ammonia synthesis under mild conditions of temperature and pressure is a new grail for its production process based on green hydrogen and intermittent renewable energy sources. Ru/LaScSi and Ru/CeTiGe are investigated with an approach combining DFT calculations and 15N/14N homomolecular exchange experiments. Ru/LaScSi is the most active of both catalysts. It has electride-like properties which are enhanced when partially hydrogenated leading to higher activity in nitrogen equilibration reaction. Ru/CeTiGe, relatively active despite the absence of electride-like character, is proposed to produce NH3 following the associative mechanism with the assistance of absorbed H.

The powerful combination of steady state isotopic transient kinetic analysis (SSITKA) and operando infrared spectroscopy (IR) was applied to study the CO oxidation reaction on Pd-supported Al2O3 catalyst at low temperature. The aim was to reveal the true role of hydrogen‑carbonate species in the reaction mechanism. The SSITKA-IR experiments, conducted in presence and absence of CO2 in the gas feed, have confirmed that hydrogen‑carbonate species behave as spectator species in the reaction. Its formation was due to re-adsorption of the CO2 product itself on the alumina surface as confirmed by the direct 12CO2/13CO2 exchange observed on the bare support.

Coke formation inside heterogeneous reactors is an important industrial problem that leads to reduced catalyst efficiency. However, this study aims to prove the benefits of coke build-up in improving catalyst performance. The formation and decomposition of coke on six different zeolite structures was studied. The dissociation kinetic model of the spent catalysts during the toluene alkylation with 1-heptene inside a stainless-steel autoclave reactor at different temperatures was carried out. Various techniques (XRD, XRF, TPO, CHNS and TGA-DTG) were used. It was found that the conversion and selectivity of the desired product were higher on the parent H-mordenite and the dealuminated H-beta catalysts with conversions of 85.3% and 84.67%, respectively, at a 360 min reaction time. This was attributed to the reduction of the ratio of hard:soft coke. It is confirmed that the decomposition activation energies of hard coke, 140.1–202.6 kJ/mol, are much higher energies than those of soft coke, 89.9–118.7 kJ/mol. It is also noted that the hypothesis of pore mouth catalysis is dominated by non-polyaromatic coke on the surface of the H-beta catalysts, while the hypothesis is dominated by polyaromatic coke on the surface of the H-mordenite catalysts.

Fischer–Tropsch to olefins (FTO) reaction is an important non-petrochemical route to produce light olefins. Iron is the most widely used and easily obtainable metal catalyst with great potential in FTO. Combine micro and relatively macro perspectives, this review briefly summarizes the recent research progress related to the synthesis of light olefins via Fe-based FTO catalysts by focusing on the addition of various supports and promoters, while elucidating the effects of novel catalyst configurations and preparation methods on catalytic performance. Finally, the future application and research of Fe-based catalysts applied in FTO are discussed.

Coal fly ash (CFA) is an alternative carrier of selective catalytic reduction (SCR) catalyst, but its reactivity is usually poor. Herein, the alkali-acid combined activation was proposed to prepare the CFA-supported high-temperature SCR catalyst. The results revealed that 1.2 g/gCFA of NaOH and 0.6 g/gCFA of H2SO4 was the optimal CFA activation condition. The NaOH first destroyed the quartz crystal over the CFA, generating the Si-OH groups. Subsequently, H2SO4 enhanced the extraction of aluminates and enriched the acid sites, which promoted the standard SCR. Besides, the generated porous fragments facilitated the dispersion of Fe3+ species and improved the fast SCR.

S-scheme-based hydrothermal synthesis of SiO2@CuFe2O4-AgI composites was effectively described in this work. The photo-degradation of hazardous dyes like methylene blue (MB) and methyl orange (MO) was utilized to test nanocomposites with variable weight percent of AgI for photocatalytic activity in the visible range. In terms of photocatalytic activity, SiO2@CuFe2O4-AgI with a 15% AgI loading beat both pure and hybrid composites. In terms of MO degradation, the hybrid composite with 15% AgI loading degrades 16 times and 8 times faster than pristine CuFe2O4 and AgI samples, respectively, while in terms of MB degradation, it degrades 18.67 times faster and 9.33 times faster than pristine samples. The increased surface area decreased the recombination rate of photogenerated e− -h+ pairs, quicker separation of photogenerated carriers, and high redox capacity of SiO2@CuFe2O4-AgI (15%) all contribute to improved photocatalytic performance. The hybrid composite is chemically stable and reusable even after 10 cycles. Because of the coordinated Fermi level between CuFe2O4 and AgI, SiO2 acts as a transfer bridge for electrons in a layered structure. Furthermore, the scavenger experiment demonstrates that •O2-, •OH, and h+ are significant reactive species that efficiently aided the photodegradation of dyes. Current research proposes a novel and cost-efficient method for creating a stable semiconductor-based photocatalytic system and a viable strategy for future applications.

Hydrogenation and hydrodeoxygenation (HDO) of 2-, 3- and 4- methoxyphenol was studied in the liquid phase over Rh/silica at 303–343 K and 3 barg hydrogen pressure. The order of overall reactivity was 3-methoxyphenol >2-methoxyphenol >4-methoxyphenol. The route to HDO products was direct from the aromatic species, while hydrogenation and HDO take place on different sites. When 2MP was competitively hydrogenated with 3MP, 2MP inhibited hydrogenation of 3MP but allowed HDO. Using deuterium revealed that cyclohexane was not formed from cyclohexanol and that mechanistically the route to the mono-HDO products was not the same as that to cyclohexane.

This study reports the kinetics of free fatty acids esterification in waste frying oil, based on a simpler non-conventional pseudo first-order homogeneous reaction mechanism using a highly-efficient acid heterogeneous catalyst derived from seeds of Açaí (Euterpe oleracea Mart.), subjected to changes in temperature, catalyst dosage, MeOH:Oil ratio, and stirring speed. Statistical analyses revealed significant effects all four conditions (p < .05) on the reaction's apparent rate constant (k1) over their different pre-defined levels. Reaction mechanism was inferred to be fundamentally acid ionic exchanges with the oil/water film on catalyst's surface, neglecting kinetically controlled liquid-to-liquid splitting and autocatalyzed esterification.

The study investigated the partial oxidation of hexafluoropropene over CuO catalyst with molecular oxygen in a continuous flow fixed bed reactor. The catalysts were characterized using various techniques, and the results confirmed catalyst's structure-reactivity correlation. The major products were hexafluoropropene oxide (HFPO) and carbonyl fluoride, with minor trifluoroacetyl fluoride produced when the catalyst had significantly declined in primary activity. The maximum selectivity of 52.5% HFPO was obtained at 13.4% hexafluoropropene conversion at 4.5 bar and 453 K. The proposed redox mechanism kinetic model was in adequate agreement with the experimental data (R2 = 0.97 for COF2 and 0.67 for HFPO).

This paper presents a critical review of recent advances in the processes of converting CO2 and CH4 gases into fine chemicals using plasma-assisted catalysis. The general principles of plasma-catalytic processes are summarized, presenting schematics and operation principles of typical plasma reactors for applications in catalysis. The applications of plasma in various catalytic CO2 and/or CH4 conversion processes are discussed and the advantages of using plasma in catalysis compared to traditional thermal processes are highlighted. Among all the plasma reactors presented in the review, the use of the DBD reactor for CO2 and CH4 conversion is described in detail due to its simplicity, possible configuration changes, easy catalyst replacement and its mild operating conditions during the process compared to other types of plasma reactors. The paper presents also the postulated reaction paths and a comparison of the efficiency and the selectivities obtained during the dry reforming of methane process using various type of reactors. Current challenges and outlook for plasma-assisted catalytic processes are also presented.

In this work, Bi2WxMo1–xO6 solid solutions and Bi2WO6/g-C3N4 composites were synthesized by a simple hydrothermal method, characterized by a complex of physicochemical methods and used in the decomposition of organic pollutants under visible light to comprehensively compare different modulating techniques. The highest efficiency was detected for Bi2W0.5Mo0.5O6 in the degradation of methylene blue (conversion of 52.9%, TON = 0.022), indicating the attractiveness of the doping strategy. Excellent results were achieved with small amounts of H2O2 in the photodegradation of methylene blue (conversion of 97.9%, TON = 0.040) and phenol (conversion of 81.2%, TON = 0.056).

Catalytic methane decomposition is believed to be an economic and environmental friendly route for the production of COx free hydrogen and high quality carbon nanotubes. However, the development of active and stable catalysts remains a significantly challenging research topic. This study focuses on the development of highly active and stable silica-supported Fe-based catalysts for the thermal decomposition of methane into hydrogen and high quality carbon nanotubes. A series of Fe/SiO2 catalysts with varying Fe loading in the range between 25 wt% and 100 wt% were synthesized by the solution combustion synthesis (SCS) method. The synthesized catalysts were characterized by various bulk sensitive and surface sensitive analytical tools, such as SEM, XRD, HRTEM, BET and Raman spectroscopy. All supported catalysts exhibited comparatively high activity than the unsupported 100 wt% Fe (denoted as 100F) catalyst which was the least active. Moreover, the catalytic activity in terms of methane conversion, methane decomposition rate, growth activities as well as carbon yields increased with an increase in the Fe loading. At an operating temperature of 650 °C and a GHSV of 8000 h−1, the 75FS catalyst, with a composition of 75 wt%Fe/SiO2, demonstrated the highest methane decomposition rate of 0.75gCH4/g-cat.h among the investigated catalysts. Additionally, after achieving initial stability at about 120 min, this catalyst remained active throughout testing on stream for 900 min. TEM and SEM analysis of the spent catalyst showed that the supported 75FS catalyst produced multi-walled carbon nanotubes with uniform diameters of 28 nm and with Id/Ig ratio of 0.454 whereas the unsupported 100F catalyst mainly produced graphene sheets.

In this paper, CuMn doped catalysts were prepared by using SiO2, γ-Al2O3 and Beta molecular sieve as carriers, and propane catalytic degradation experiments were carried out. The modified H-Cu-Mn-Beta molecular sieve catalyst has large pore size, smooth surface, good adsorption performance and the best catalytic degradation effect on propane. The optimum process conditions were obtained by single factor test: Cu: Mn = 2:1, pickling temperature 50 °C, microwave calcination temperature 500 °C, holding time 40 min. The catalyst prepared under this condition has high catalytic activity. When the temperature was 500 °C, the degradation rate remained above 82.7% within 36 h.