Temperature-programmed Desorption Of Ammonia Research Articles

Catalytic activity of Zr/CeO2-Al2O3 catalyst for diesel soot oxidation: synthesis, characterization, and performance evaluation.

Diesel soot is a significant contributor to air pollution. Soot particles present in diesel engine exhaust have a negative impact on the environment and human health. Diesel oxidation catalysts (DOCs) and diesel particulate filters (DPFs) currently use noble metal-based catalysts for soot oxidation. Due to the use of noble metals in the catalyst, the cost of diesel after-treatment systems is steadily rising. As a result, diesel vehicles have become commercially less viable than gasoline vehicles and electronic vehicles. The study focuses on an alternative diesel oxidation catalyst with efficiency similar to that of a noble metal catalyst but with a much lower cost. CeO2-Al2O3 catalysts are known for their oxygen storage capacity and high redox activity, making them suitable for soot oxidation. Adding Zr to these catalysts has been shown to influence their structural and chemical properties, significantly affecting their catalytic behavior. Therefore, the current study is focused on using Zr/CeO2-Al2O3 as a substitute for noble metal-based catalysts to enhance its performance for diesel soot oxidation in automotive exhaust. Evaporation-induced self-assembly (EISA) was used to prepare 1, 3, and 5 weight (wt) % Zr supported mesoporous CeO2-Al2O3 catalysts. Morphological, structural, and physicochemical properties of the synthesized catalysts were examined using Brunauer-Emmett-Teller (BET) absolute isotherm, Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Temperature programmed reduction (TPR), and Temperature-programmed desorption of ammonia (NH3-TPD). XRD, BET, and SEM data confirmed that the catalysts were mesoporous and low-crystalline with a high surface area. The soot oxidation activity of the catalysts was evaluated using a thermogravimetric analysis (TGA) technique. The loose contacts soot oxidation activity test suggested that 50% oxidation of soot occurred at 390°C in the absence of a catalyst. T50 of CeO2-Al2O3 catalyzed soot oxidation was 296°C. Adding Zr to the catalyst significantly improved catalytic activity for diesel soot oxidation. We observed a further drastic change in T50 of soot over 1, 3, and 5% Zr/CeO2-Al2O3, which were 220°C, 210°C, and 193°C, respectively. According to these results, incorporating Zr into the CeO2-Al2O3 catalyst significantly improved the oxidation process of soot.

Performance of sulfided NiMo catalyst supported on pillared bentonite Al and Ti under hydrodeoxygenation reaction of guaiacol

Bio-crude oil is known to be sustainable, eco-environmentally, and an alternative energy source produced by biomass pyrolysis. However, its quality remains relatively low due to a higher oxygen concentration compared to liquid fuels from fossils. Therefore, an upgrading process is necessary through the catalytic hydrodeoxygenation (HDO) process. This work synthesized pillared bentonite using Al and Ti metals as the pillaring agent to produce Al-PILC and Ti-PILC as catalyst support for sulfided NiMo. Their catalytic activity in HDO reaction using guaiacol as a model compound of bio-crude oil were also evaluated. Characterization of the bentonite-pillared materials, including Al-PILC, Mo/Al-PILC, NiMo/Al-PILC, Ti-PILC, Mo/Ti-PILC, and NiMo/Ti-PILC, was performed using Surface Area Analyzer, X-ray Diffractometer (XRD), Temperature-Programmed Desorption of ammonia (NH3-TPD), X-Ray Fluorescence (XRF), and Scanning Electron Microscope (SEM) techniques. The characterization results confirm the pillarization process of bentonite using Al and Ti metals as the pillaring agent, and the preparation of the NiMo catalyst using the stepwise impregnation method was successfully prepared. The NiMo/Ti-PILC catalyst performs a superior conversion value on the HDO guaiacol reaction than other catalysts. A well dispersion of Mo and Ni metals on the surface support (NiMo/Ti-PILC), thus creating numerous active sites of the catalyst after the sulfidation. Variations in time and temperature during the HDO guaiacol reaction significantly affected the conversion.

Simple Fabrication of Hydrophobicity-Controlled Fe-ZSM-5 for Aqueous-Phase Partial Oxidation of Methane with Hydrogen Peroxide

Surface hydrophobicity is an important factor in controlling the catalytic activity of heterogeneous catalysts in various reactions, particularly liquid-phase reactions using water as the (co)solvent. In this study, the surface hydrophobicity of Fe-ZSM-5 was successfully controlled using a simple coating method in which furfuryl alcohol was used as the carbon precursor. Various techniques, such as N2 physisorption, temperature-programmed desorption of ammonia, and contact angle measurements of water droplets, were used to characterize the catalysts. Fe-ZSM-5 catalysts with different degrees of hydrophobicity were used for the aqueous-phase selective oxidation of methane with H2O2. The positive effect of the surface carbon coating on the catalytic performance was confirmed when the carbon content was not sufficiently high to block the pores.

Biodiesel Production via Transesterification Reaction over Mono- and Bimetallic Copper-Noble Metal (Pt, Ru) Catalysts Supported on BEA Zeolite

This work focuses on the study of biodiesel production from commercial rapeseed oil and methanol via transesterification reactions on monometallic copper and bimetallic copper–noble metal (platinum, ruthenium) catalysts supported on BEA zeolite. The catalysts were prepared by wet impregnation method on the hydrogen form of BEA zeolite. As part of the study, the physicochemical and catalytic properties of the prepared catalytic materials were determined. The catalytic activity tests were carried out in the transesterification reaction over prepared catalysts at 220 °C for 2 h in an autoclave. The physicochemical properties of the obtained catalysts were investigated by X-ray diffraction (XRD), specific surface area and porosity (BET), a scanning electron microscope equipped with an energy dispersive spectrometer (SEM–EDS) and temperature-programmed desorption of ammonia (TPD-NH3) method. The results of the catalytic activity showed the promotional effect of the noble metal on the TG conversion and FAME efficiency of copper catalysts in the biodiesel production process. The most active catalyst turned out to be the calcined 5%Cu–1%Ru/BEA catalyst, which showed the highest TG conversion of 85.7% and the second highest FAME efficiency of 58.4%. The high activity of this system is explained by its surface acidity and large specific surface area.

Effect of Bimetallic Co-Cu/Dolomite Catalyst on Glycerol Conversion to 1,2-Propanediol

This present study examines the efficacy of using dolomite (Dol, CaMg(CO3)2)-supported copper (Cu) and cobalt (Co) bimetallic and monometallic catalysts for the hydrogenolysis of glycerol to propylene glycol (PG; 1,2-PDO). The proposed catalysts were generated using the impregnation process before they were calcined at 500°C and reduced at 600°C. Advanced analytical techniques namely Brunauer, Emmett, and Teller (BET) method; the Barrett, Joyner, and Halenda (BJH) method; temperature-programmed desorption of ammonia (NH3–TPD), hydrogen-temperature programmed reduction (H2-TPR), X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM) were then used to characterise the synthesised catalysts, whose performance was then tested in the hydrogenolysis of glycerol. Of all the synthesised catalysts tested in the hydrogenolysis process, the Co-Cu/Dol bimetallic catalyst performed best, with an 80.3% glycerol conversion and 85.9% PG selectivity at a pressure of 4 MPa, a temperature of 200°C, and a reaction time of 10 hours. Its high catalytic performance was attributed to effective interactions between its Co-Cu-Dol species, which resulted in acceptable acidity, good reducibility of metal oxide species at low temperatures, larger surface area (15.3 m2 g-1), large-sized particles, fewer pores (0.032 cm3 g-1), and smaller pore diameter (0.615 nm).

Enhancing CO and H2 Production in Propane Dry Reforming in Excess of CO2.

This study focuses on addressing the challenges in the dry reforming of propane, a process historically marked by low syngas yields and only moderate conversions of CO2 and propane. The primary objective was to enhance CO2 utilization and boost the selectivity of syngas (CO and H2) production using titania-based catalysts. For synthesizing these catalysts, an impregnation method was employed with subsequent characterization through X-ray diffraction (XRD), N2 adsorption-desorption, ammonia temperature-programmed desorption (TPD), and hydrogen temperature-programmed reduction (TPR). The titania-based catalysts generally possess weak acidic strength, with each catalyst displaying a unique reduction profile. The dry reforming process using these catalysts resulted in varying levels of propane conversion, with V/Ti, Ir/Ti, Al/Ti, and Zr/Ti catalysts showing distinct efficiencies. Notably, the Ir/Ti and V/Ti oxide catalysts achieved the lowest selectivity for generating intermediate byproducts such as methane, ethane, ethylene, and propylene while successfully promoting higher syngas CO and H2 production alongside stable propane conversion. When exposed to excess CO2, each catalyst consumed differing amounts of CO2 molecules. Particularly, the Ir/Ti and V/Ti oxide catalysts demonstrated enhanced activity in promoting CO2 reactions with intermediate radical species, facilitating carbon-carbon (C-C) bond dissociation and leading to increased syngas production. This study offers valuable insights into the potential of titania-based catalysts in improving the efficiency and selectivity of propane dry reforming processes for blue hydrogen.

Role of the surface layer of epoxy resin

Water pollution threatens human health, and the safe supply of drinking water has been recognized as a problem worldwide. The increasing accumulation of heavy metals in water from various sources has led to the search for effective and environmentally friendly treatment methods and materials for their removal. To impart the necessary characteristics to minerals, in particular to improve sorption properties, one of the methods is modification. Modern technologies using sorbents require qualitatively new sorption materials with increased capacity and high selectivity of action. Epoxy resins are widely used as a base material in the coating field due to their advantages including adsorption properties. In this work, shungite from the Koksu deposit and Shankhanai zeolite were used as natural sorbents for modification. The purpose of this work is to study the interaction of epoxy resin ED-20 with the surface of a natural sorbent through a layer of polyethylene polyamine. Methodology. To study the surface of the prepared samples, methods such as infrared spectroscopy, gravimetry and the temperatureprogrammed desorption method were used. Results and discussion. This article presents the results of IR spectroscopic analysis of natural sorbents shungite and zeolite modified with epoxy resin ED-20 and polyethylene polyamine. The obtained surface epoxy layers were studied for resistance to aqueous environments of varying acidity for 90 days. The acid-base properties of the surface layers of modified sorbents were studied by the method of temperature-programmed ammonia desorption. Conclusion. By modifying shungites and zeolites with polyethylene polyamine, followed by cross-linking them on the surface of a natural mineral with ED-20 epoxy resin, a durable layer of epoxy resin was obtained.

Preparation of Solid Superacid SO42-/ZrO2 and SO42-/ZrO2-MxOy (M=Ce, Co, Mn, and Zn) and Its Application in Toluene Nitration.

The nitration reaction of aromatic compounds is one of the extensively studied chemical reactions that result in the manufacturing of various industrial products applied in pharmaceuticals, dyes, perfumes, and explosives. A series of modified sulfated zirconia (SZ) catalysts SO42-/ZrO2-MxOy (M=Ce, Co, Mn, Zn, and M/SZ) doped with different metal elements by a coprecipitation method were investigated in the toluene nitration reaction. Various characterization techniques (X-ray diffraction, Brunauer-Emmett-Teller, thermogravimetric analysis, X-ray photoelectron spectroscopy, and temperature-programmed desorption of ammonia) indicated that doping metal elements in SZ led to excellent catalytic properties, increasing the specific surface area of the catalyst and facilitating the formation of a stable tetragonal zirconia phase. Doping zinc and cobalt in SZ enhanced the acidity of the catalyst and formed stronger acidic sites, promoting the generation of nitronium ions and providing more active sites for the toluene nitration reaction. Additionally, it reduced the loss of sulfate ions in the catalytic system that helped in improving the stability of the catalyst. Under the same conditions, the catalytic activity of toluene nitration reaction demonstrated the following order: Zn/SZ > Ce/SZ > Co/SZ > Mn/SZ > SZ, with the zinc-doped SZ catalyst exhibiting the best catalytic performance, achieving a toluene conversion rate of 78.58% and a para/ortho nitrotoluene ratio of 0.67.

Catalytic performance of desilicated HZSM-12 for benzylation reaction of benzene with benzyl alcohol

The catalytic production of diphenylmethane from the reaction of benzene with benzyl alcohol was investigated using HZSM-12 and desilicated HZSM-12 that was obtained by treating ZSM-12 with 0.2M NaOH solution at 85 ?C for 60 min. The untreated and alkaline treated ZSM-12 zeolites were characterized by X-ray diffraction, nitrogen adsorption/desorption isotherms, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, and temperature-programmed desorption of ammonia. The desilicated HZSM-12 showed promising catalytic performance with benzyl alcohol conversion of 100% and the selectivity to diphenylmethane of 74% and 87% in 4 h and 8 h reaction time, respectively. The reaction parameters affecting benzyl alcohol conversion and product distribution were also presented. The activities of fresh and regenerated catalysts were compared, and characterization results indicated that the occluded organic molecules decreased the number of acidic sites of the catalyst after the reaction and regeneration.

IMPROVED ACIDITY OF MESOPOROUS ZrO2-WO3 THROUGH NH3-AIR SUBSECTION-CALCINATION TREATMENT

ZrO2-WO3 mixed metal oxides are important solid acid catalysts, and typically, ammonia gas calcination reduces their acidity. However, in this study, we introduce an updated NH3 calcination technique that can increase the acidity of mesoporous ZrO2-WO3 solid acids. Their structures and acid properties were thoroughly characterized through X-ray diffraction (XRD), N2 adsorption measurement, pyridine-adsorbed infrared spectroscopy (Py-IR), temperature-programmed desorption of ammonia (NH3-TPD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis-DRS) analysis. The resulting materials exhibit remarkable activity in the Friedel-Crafts (F-C) reaction of anisole and benzyl alcohol. Our investigations showed that the subnanometer WOx clusters act as the most active sites for the F-C reaction, and NH3-air calcination is essential for the formation of WOx clusters. This treatment not only enhances acidity but also provides a novel method of obtaining acidic ZrO2-WO3 mixed metal oxides. Most importantly, it presents a fresh approach for regulating the formation of WO3 clusters and catalytic activity.

Performance Study of Ni/Si-MCM-41 Catalysts, Synthesized with Different Silica Sources, and their Application on Methane Dry Reform to Produce Green Hydrogen

The present work carried out an extensive and deepened study regarding the physicochemical characteristics of two Si-MCM-41-type supports, synthesized employing two distinct silica precursors, tetraethyl orthosilicate (TEOS) and rice husk ash (RHS), with the dispersion of nickel on the surface of the catalytic support. The direct influence of the active phase dispersion was analyzed, making a relationship with the formation of coke and with its performance on methane dry reform (DRM). The catalysts were prepared with 5, 10, and 20% (m/m) of Ni by wet impregnation method (with excess solvent), calcined at 800 ºC for 6 h, and characterized by the techniques of scanning electron microscopy and energy dispersive spectroscopy (SEM/ EDS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET)/Barret-JoyerHalenda (BJH), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), temperature-programmed ammonia desorption (TPD-NH3), and H2-temperature-programmed reduction (TPR). The DRM experiments were carried out at 800 °C for 24 h with a 1:1 CH4:CO2 molar ratio. Analyzes of gaseous products were performed in gas chromatography (GC) and the coke produced was estimated by temperature-programmed oxidation (TPO). The best reaction results were obtained for catalysts with 20% nickel, which were selective and stable within 24 h of reaction. Comparing the TEOS and RHS catalysts for 20% Ni, the DRM results were very similar. The catalysts on RHS support demonstrated a significant low formation of coke, which can be considered negligible in a 24 h reaction.

Ionothermal synthesis of ZSM-5/AlPO4-5 composite zeolites and their catalytic performances in the methanol-to-olefin reaction

Composite zeolites, specifically ZSM-5/AlPO4-5 ([E]-Z5/Al5, [B]-Z5/Al5 and [H]-Z5/Al5), were prepared using tri-substituted imidazolium bromide ionic liquids (ILs). The ILs used were 1-ethyl-2,3-dimethylimidazolium bromide ([EMMIM]Br), 1-butyl-2,3-dimethylimidazolium bromide ([BMMIM]Br) and 1-hexyl-2,3-dimethylimidazolium bromide ([HMMIM]Br). The structure, morphology and acidity of the composite zeolites were analyzed using various techniques, such as X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), N2 isothermal adsorption-desorption, thermogravimetric analysis (TGA), temperature-programmed desorption of ammonia (NH3-TPD) and nuclear magnetic resonance spectroscopy (NMR). The catalysts obtained demonstrate outstanding performance in the methanol-to-olefin (MTO) reaction, with a catalytic lifetime extended by approximately tenfold and an approximately 10 % increase in the yield of light carbon olefins compared to the traditional hydrothermal Z5/Al5 catalyst. There is a strong relationship between the selectivity and stability of the MTO reaction with the optimized grain size and catalyst acidity.

Heterogeneous La and CeOx co-promoted SAPO-11 catalyst for catalytic upgrading of cellulose-derived volatile and methanol into hydrocarbon-rich fuels

In this paper, a series of La–Ce co-doped SAPO-11 catalysts with various La to Ce ratio were developed via wet impregnation method then employed in catalytic cellulose and methanol co-pyrolysis to produce hydrocarbon-rich biofuels. Comprehensive characterization technologies including X-ray diffraction, X-ray photoelectron spectroscopy, N2 physisorption, scanning electron microscope, transmission electron microscope, ammonia temperature-programmed desorption, Pyridine-infrared, and thermal gravimetric analyzer, were conducted to unveil the physicochemical properties, structure properties and acidity of as-prepared catalysts. Additionally the product content; aromatic selectivity and synergetic effect were also investigated. Additionally possible conversion pathway, deactivation mechanism and reusability were also deduced. La and Ce showed a certain synergetic effect and exhibited superior catalytic deoxygenation activity due to La–O and Ce-Ox species, suitable Brønsted acidity, abundant oxygen vacancies and enhanced mesopores structure, which was facilitated to promote the selectivity of hydrocarbon. Higher La content was fascinated to generate furans and ketones compounds, due to lower Brønsted acid site and smaller specific surface area. In contrast, higher CeOx content was beneficial to hydrocarbon formation via Diels-Alder reaction and dehydro-aromatization due to higher Brønsted acid site, total acidity, higher specific surface area, mesoporous pore volume as well as strong oxygen affinity of CeOx. The maximum proportion hydrocarbon, aromatics and minimum contents coke was obtained over 1La–1Ce/SAPO-11 were 77.96 %, 55.82 % and 9.81 %, respectively. Additionally, 1La–1Ce/SAPO-11 catalyst exhibited outstanding reusability and stability after four cycles; nearly ∼96 % relative content of hydrocarbon was maintained after regeneration test. Hence, the insight into the synergetic catalysis between La and CeOx species could provide a new potential possible pathway for design and synthesized efficient and eco-friendly bimetallic catalyst for selective catalytic deoxygenation organic solid waste biomass for valuable chemicals.

MOF-199 and Ni-BTC: Synthesis, Physicochemical Properties, and Catalytic Activity in Oxidation of 5-Hydroxymethylfurfural

Platform chemical 2,5-furandicarboxylic acid (FDCA) has potential applications to replace petroleum-based chemicals. Metal Organic Framework (MOF) can be used as a catalyst to oxidize 5-hydroxymethylfurfural (HMF), producing FDCA. MOF-199 and Ni-BTC were synthesized using solvothermal method with trimesic acid (benzene 1,3,5-tricarboxylic acid/H3BTC) as a linker and Cu or Ni as a metal nod. The physical and chemical properties of catalysts were discovered through characterization using X-ray Diffraction (XRD), Fourier Transform Infra Red (FT-IR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy - Energy Dispersive X-ray (SEM-EDX), and Ammonia Temperature-programmed Desorption (NH3-TPD). FDCA and its intermediate compounds were produced by converting HMF to FDCA in a small glass batch reactor. The yields of products were then determined by High-Performance Liquid Chromatography (HPLC). HPLC results indicated that there was no DFF (2,5-diformylfuran) signal, indicating that FDCA was formed by FFCA (5-formylfuroic acid) and HMFCA (5-hydroxymethylfuroic acid) formation reaction pathway. The maximum conversion (71%) was obtained using Ni-BTC as a catalyst at 130 °C for 5 h, with FDCA yield of 61.8%. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Effect of Sn(II)/Sn(IV) additive on the catalytic combustion of diethylamine and N2 selectivity over CeZrOx catalyst

The synthesis of CeZrSnOx by co-precipitation with different valence-state of Sn for diethylamine combustion is novel and intriguing. In this research, the Sn(II)/Sn(IV)-doped CeZrOx catalysts (CeZr(Sn)Ox-(Sn2+) and CeZr(Sn)Ox-(Sn4+)) were facilely prepared using the co-precipitation method, and their catalytic activities on destruction of diethylamine were evaluated. Detailed characterizations of the catalysts were conducted using X-ray photoelectron spectrometer (XPS), X-ray powder diffraction (XRD), hydrogen-temperature programmed reduction (H2-TPR), temperature programmed ammonia desorption (NH3-TPD) and so on. For diethylamine combustion, CeZr(Sn)Ox-(Sn2+) showed higher activity and nitrogen selectivity than other catalysts, and a high conversion of diethylamine (>90 %) at 250 °C was obtained. After hydrothermal aging treatment, a high conversion (>90 %) and high N2 selectivity maintained over CeZr(Sn)Ox-(Sn2+)-H at 280 °C, indicating high hydrothermal stability of CeZr(Sn)Ox-Sn2+. Owe to the large specific surface area (SSA), high oxygen mobility and strong redox performance, and the synergy between metal elements in CeZr(Sn)Ox-Sn2+ catalysts, the catalytic properties were enhanced. Moreover, Sn2+/Sn4+ ratio in the catalyst and strong acidic sites on the surface of the catalyst both had significant impacts on the catalytic activity and N2 selectivity of the catalyst. Finally, the mechanism of diethylamine combustion over CeZr(Sn)Ox-Sn2+ was obtained by analyzing the reaction through in-situ diffuse reflection infrared Fourier-transform spectrum (in situ DRIFTS) test.

Oxidation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid over CuO and NiO modified natural sourced hierarchical ZSM-5

The platform molecule 2,5-furandicarboxylic acid (FDCA) has potential applications. FDCA can be synthesized through the oxidation of 5-hydroxymethylfurfural (HMF). In this study, HMF oxidation to FDCA was conducted over ZSM-5-based catalysts from natural sources. ZSM-5 was impregnated with CuO and NiO oxide metals to increase their acidity and oxidizing ability. Characterization of the catalyst utilizing x-ray diffraction (XRD), infrared spectrophotometer (FT-IR), scanning electron microscopy-energy dispersive x-ray (SEM-EDX), Brunauer-Emmet-Teller (BET) surface area analysis, and temperature-programmed desorption of ammonia (NH3-TPD) led to the discovery of its physicochemical characteristics. The results showed that synthesized ZSM-5 had hierarchical pores with a surface area of 123.58 m2/g. Impregnation with CuO and NiO increased the acidity by 22.5 and 3.04 % for CuO/ZSM-5 and NiO/ZSM-5, respectively. In a small glass batch reactor, HMF was converted to FDCA, and the products were analyzed using High-Performance Liquid Chromatography (HPLC) to determine the yield of FDCA and the intermediate compounds, such as 5-hydroxymethylfuroic acid (HMFCA), 5-formylfuroic acid (FFCA), and 2,5-diformylfuran (DFF). HPLC results showed no DFF signal, indicating the formation of FDCA from HMF through HMFCA and FFCA. The highest conversion (99.2 %) was obtained using a NiO/ZSM-5 catalyst at a temperature of 130 °C for 4 h, with FDCA yield of 88.9 %.

Thermokinetic Study of Catalytic Pyrolysis of Medium-Density Fiberboards over Beta-Zeolite-Supported Platinum

Catalytic pyrolysis is an attractive alternative for converting biomass into energy and chemicals, replacing fossil sources. Efficient catalysts can be used to remove compounds containing oxygen during pyrolysis, improving the bio-oil properties and thus being an important route towards sustainability. Catalytic pyrolysis of medium-density fiberboard (MDF) residues over platinum (1%) supported on beta zeolite was carried out using a biomass/catalyst ratio of 1.0/0.2. The catalysts were characterized via Fourier transform infrared spectroscopy, flame atomic absorption spectrometry, X-ray diffraction, nuclear magnetic resonance, temperature-programmed reduction, and temperature-programmed desorption of ammonia. The thermokinetic and thermodynamic parameters were determined using the isoconversional and non-isothermal methods of Friedman, Flynn-Wall-Ozawa (FWO), and Kissinger-Ahakira-Sunose (KAS). The Friedman method was the most adequate to describe the reaction and thermodynamic parameters. The results show that the catalysts promote the reduction in activation energy compared to non-catalytic pyrolysis. Non-impregnated and impregnated catalysts showed different activation energies and thus different reactions. The addition of platinum slightly increased the activation energy due to the promotion of reactions that require more energy, for example, cracking and coke deposition.

In situ topologically prepared Co–Zn-based mixed metal oxide bimetallic catalysts for guaiacol hydrodeoxygenation

Bio-oil, derived from biomass pyrolysis, can be used as an alternative to fossil fuels after treatment through hydrodeoxygenation (HDO) reactions. In this study, a series of Co–Zn-based mixed metal oxide (Co-Zn-MMO) catalysts were synthesized using Co–Zn-based layered double hydroxide (Co-Zn-LDH) as a precursor. The catalysts were then used in the HDO reaction of guaiacol and larch wood-derived bio-oil. The Co–Zn-MMO catalysts were characterized via scanning electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller analysis, X-ray photoelectron spectroscopy, hydrogen-based temperature-programmed reduction, and ammonia temperature-programmed desorption techniques. Among the Co-Zn-MMO catalysts, the Co1-Zn2-MMO catalyst, with a Co-to-Zn molar ratio of 1:2, exhibited the highest acidity, the largest pore size and pore capacity, and the highest density (65.56%) of Co2+δ-Ov-Zn2-δ oxygen vacancy. These characteristics resulted from the metal–support interaction effect, leading to superior HDO activity for guaiacol. Furthermore, the Co1-Zn2-MMO catalyst effectively removed heteroatomic components from larch wood-derived bio-oil, thereby enhancing the quality of the bio-oil product.

Catalytic conversion of n-Dodecane to lower olefins hydrogen carriers over bran-shaped modified MCM-22 zeolite catalyst: SiO2/Al2O3 ratio effects

The demand-supply gap for light olefins and aromatics has been enormous in recent years. This imbalance is anticipated to grow exponentially due to their extensive use in manufacturing plastics, textiles, pharmacological intermediates, climate-neutral synthetic fuels, and hydrogen carriers. Production of light olefins through the catalytic cracking of naphtha is widely regarded as one of the most prestigious methods. Despite this, selecting an effective and efficient catalyst is one of the most challenging aspects of the scaling-up process. In this study, a highly active, modified MCM-22 catalyst has been synthesized by a hydrothermal method. Various techniques are used for the characterization of catalysts, including scanning electron microscopy (SEM), X-ray diffraction (XRD), N2 adsorption-desorption, temperature-programmed desorption of ammonia (NH3-TPD), and solid-state nuclear magnetic resonance experiments (NMR) with Al and Si. The cracking of n-dodecane to lower olefins was performed, and it was found that the conversion rates were highly correlated with the SiO2/Al2O3 ratio of the MCM-22 samples. Sample Si0.5 (SiO2/Al2O3 ∼ 28.9) showed a typical photograph of the MWW phase with a bran or flake shape in a stacking mode. The Si0.5 sample has a superior external surface area than other samples (up to ca. 130 m2/g) caused by a smaller particle with an average crystal size of around 15 nm, resulting in maximum catalytic performance towards light olefins. It was discovered that Si0.5 had a diminishing tendency in the paraffinic selectivity but had a robust selectivity for olefins (propylene and butylene in particular). This research may provide academics and the industry with new prospects for improving the catalytic cracking of n-dodecane into light olefins.

Combination of natural silica and alumina sources for synthesis of MCM-22 zeolite

Zeolite has become a promising material that can potentially play a pivotal role in resolving environmental crises. Among zeolite families, MCM-22 zeolite shows outstanding intrinsic properties associated with the topology and porous structure, offering ion-exchange advantages for catalytic activity processes. The synthesis of MCM-22 zeolite becomes challenging when concerning the cost and catalytic performance. To overcome this bottleneck, we demonstrate a sustainable route of a hydrothermal process using natural resources as starting materials. Rice husk from agricultural waste was used as a silica source while natural clays (kaolin and bentonite) were applied as alumina sources. The products from natural sources were compared with the use of commercial starting materials, e.g., NaAlO2 (for alumina) and Na2SiO3 and TEOS (for silica), in points of crystal, compositional, and morphological views. We showed that the high purity of MCM-22 zeolite can be obtained from rice husk silica (RHS) and aluminosilicate gel (ASG) extracted from kaolin, while the use of ASG extracted from bentonite tended to be unsuitable to generate the zeolite formation. We also studied the effects of reaction time and the ratio of RHS/ASG on the crystallinity and surface area of MCM-22. The architecture and acidity of an optimal product were explored by Nuclear magnetic resonance spectroscopy and Temperature-programmed desorption of ammonia, demonstrating the success of achieving well acidity.