Effect Of Different Catalysts Research Articles

Study on catalytic thermal dissolution of lignite and hydro-liquefaction of its soluble fraction for potential jet fuel

This work proposes a promising means for jet fuel production using lignite as feedstock, which is of great significance for resource utilization of low rank coals (LRCs). Thermal dissolution soluble fractions (TDSFs) were prepared and the ensuing hydro-liquefaction of the TDSFs was performed to obtain liquefied oil, which can be upgraded and refined into jet fuels. The effects of different catalysts on the catalytic thermal dissolution (TD) properties of Xilinguole (XLGL) lignite were studied. The structure of the TDSFs was analyzed and characterized. The results suggested that the catalytic TD could notably enhance TDSFs yield compared to non-catalytic TD, and the activity of the four catalysts used was in order of BF3/SBA-15＞FeS + S＞SO42-/ZrO2＞Fe2O3. The oil yield and composition, especially cyclanes content, varied with the hydro-liquefaction conditions, i.e., technical parameters including temperature, catalyst, solvent and TDSF type significantly changed the oil yield and cyclanes content, thus affecting the potential for jet fuel production. The Ni-Mo-S/γ-Al2O3 catalyst effectively promoted TDSFs hydro-liquefaction, and both conversion and oil yield increased with rising temperatures during catalytic and non-catalytic hydro-liquefaction. On the other hand, the cyclanes content in liquefied oil decreased with rising hydro-liquefaction temperatures. The TDSFs prepared at low temperatures are more suitable for jet fuel production due to its higher cyclanes content through hydro-liquefaction.

Novel Potentially Biobased Copolyesters Comprising 1,3-Butanediol, 1,4-Cyclohexanedimethanol and Dimethyl Terephthalate; Effect of Different Catalysts on Polymerization Behavior

Novel Potentially Biobased Copolyesters Comprising 1,3-Butanediol, 1,4-Cyclohexanedimethanol and Dimethyl Terephthalate; Effect of Different Catalysts on Polymerization Behavior

Effect of different catalysts and growth temperature on the photoluminescence properties of zinc silicate nanostructures grown via vapor-liquid-solid method

We explore the photoluminescence properties of zinc silicate (Zn2SiO4) nanostructures synthesized by vapor-liquid-solid (VLS) mode of growth using three different catalysts (Sn, Ag, and Mn). Different catalysts significantly influence the growth rate which in turn has an impact on the structure and hence the photoluminescence of the prepared zinc silicate nanostructures. Zn2SiO4 has a wide bandgap of about 5.5 eV and in its pure form, it does not emit in visible region due to its inner shell electronic transitions between the 3d5 energy levels. However, the incorporation of different catalysts (Sn, Ag and Mn) at different growth temperatures into the Zn2SiO4 crystal growth kinetics provides wide visible spectral range of photoluminescence (PL) emissions. PL analysis shows broad multi-band spectrum in the visible region and distinct colors (red, yellow, green, blue, cyan and violet) are obtained depending on the crystalline structure of the prepared nanostructures. The allowed transitions due to the effect of different catalysts on zinc silicate lattice offer a huge cross-section of absorption that generates strong photoluminescence. The correlation between the structural and optical properties of the synthesized nanostructures is discussed in detail. The synthesized photoluminescent nanostructures have potential applications in solid-state lighting and display devices.

Microwave catalytic co-pyrolysis of waste cooking oil and low-density polyethylene to produce monocyclic aromatic hydrocarbons: Effect of different catalysts and pyrolysis parameters

It is promising to convert waste oil and plastics to renewable fuels and chemicals by microwave catalytic co-pyrolysis, enabling pollution reduction and resource recovery. The purpose of this study was to evaluate the effect of catalysts on the product selectivity of microwave-assisted co-pyrolysis of waste cooking oil and low-density polyethylene and optimize the pyrolysis process, including pyrolysis temperature, catalytic temperature, waste cooking oil to low-density polyethylene ratio, and catalyst to feedstocks ratio. The results indicated that catalysts had a great influence on the product distribution, and the yield of BTX (benzene, toluene, and xylenes), which increased in the following order: SAPO-34 < Hβ < HY < HZSM-5. HZSM-5 was more active for the formation of light aromatic hydrocarbons as compared to others, where the concentrations of toluene, benzene and xylenes reached 252.59 mg/mL, 114.7 mg/mL and 132.91 mg/mL, respectively. The optimum pyrolysis temperature, catalytic temperature, waste cooking oil to low-density polyethylene ratio and catalyst to feedstocks ratio could be 550 °C, 450 °C, 1:1 and 1:2, respectively, to maximize the formation of BTX and inhibit the formation of polycyclic aromatic hydrocarbons.

Effects of different catalysts on light-off temperature of volatile organic components in the rotary diesel particulate filter during the regeneration

In this work, the rotary diesel particulate filter (DPF) is used as the research object, and the effects of different mass fractions of Pd and Pt catalysts and different test conditions on the light-off temperature in regeneration process are investigated through the CHEMKIN software. The results show that the light-off temperature of volatile organic components in the Pd-catalyst rotary diesel particulate filter is 110 K lower than that in the rotary diesel particulate filter without catalyst. The light-off temperature decreased with the increase of catalyst mass fraction. Pd-based catalysts with mass fractions of 0.1%, 0.5%, and 1.0% had significantly higher effects on CH4 combustion than Pt-based catalysts. While Pt-based catalysts with mass fraction of 2.0% show the best light-off performance among all catalysts. The conversion rate of the 2.0% Pt-based catalysts reaches 62.27% at 623 K and 100% at 698 K. The research results under different test conditions show that Pd dispersion around 70% has the lowest light-off temperature. The light-off temperature of CH4 is lower at lower air flow rates. As the air flow increases, the light-off temperature increases. The intake pressure and HC concentration have small effects on the light-off temperature of CH4. The increases of water vapor volume fraction lead to a gradual increase in the light-off temperature of CH4.

Hierarchical Porous MIL-101(Cr) Solid Acid-Catalyzed Production of Value-Added Acetals from Biomass-Derived Furfural.

Considering economic and environmental impacts, catalytic biomass conversion to valuable compounds has attracted more and more attention. Of particular interest is furfural, a versatile biorefinery platform molecule used as a feedstock for the production of fuels and fine chemicals. In this study, the Cr-based metal-organic frameworks (MOFs) MIL-101 were modified by chlorosulfonic acid, and MIL-101 was changed into a hierarchical MOF structure with smaller particles and lower particle crystallinity by CTAB, which significantly improved the acidic sites of the MOFs. The original and modified MIL-101(Cr) catalysts were characterized by XRD, N2 adsorption-desorption, SEM, TEM, and FT-IR. The effects of different catalysts, reaction temperature, catalyst amount, and alcohol type on the reaction were studied. Under the action of the MOFs catalyst, a new mild route for the condensation of furfural with various alkyl alcohols to the biofuel molecules (acetals) was proposed. The conversion route includes the conversion of furfural up to 91% yield of acetal could be obtained within 1 h solvent-free and in room-temperature reaction conditions. The sulfonic acid-functionalized MIL-101(Cr) is easy to recover and reuse, and can still maintain good catalytic activity after ten runs.

Organic acid-assisted catalytic wet torrefaction of oil palm trunks (OPT)

Oil palm trunks (OPT) are attractive bio-fuel sources given their abundant availability. Nonetheless, the inherent properties of these biomass can lead to their inefficient use as bio-fuel directly. This work utilizes four organic acids (i.e., acetic, formic, levulinic, and citric acid) as catalyst in wet torrefaction to enhance the fuel properties of OPT hydrochar. In this study, the effects of different catalysts, catalyst concentrations, and residence times on the fuel properties of OPT hydrochar are analyzed. To study the effect of residence time, 0.2M of acid concentration was used for all four acids at 220 °C for 3 hr and 24 hr. Meanwhile, study on the effect of catalyst concentration was performed at 220 °C for 24 hr at 0.2M and 1.0M for all four acids. Increasing the residence time decreased the solid yield of OPT hydrochar treated in deionized water, acetic, formic, and levulinic acid, while wet torrefaction in citric acid results in close solid yield value in both residence time. The energy yield was observed to decrease in all liquid medium with increasing residence time except for formic acid and citric acid. On the other hand, increasing the acid concentration increased the OPT hydrochar solid yield in all acids except formic acid and the highest energy yield of 77.08% was obtained from wet torrefaction in 1.0M of citric acid at 220 °C for 24 hr. In summary, citric acid is an environmentally friendly acid to be used as catalyst to enhance the fuel properties of OPT hydrochar. Further study on the reaction mechanisms that governs such fuel properties enhancement with citric acid is warranted.

Hydrogen-rich syngas from wet municipal solid waste gasification using Ni/Waste marble powder catalyst promoted by transition metals.

Gasification of wet municipal solid waste (MSW) coupled with in-situ CO2 capture is an attractive option for MSW disposal, allowing chemical and energy recovery. In this study, the Ni-CaO based catalysts were prepared with waste marble powder (WMP) as an alternative to CaO and promoted by different transition metals (i.e., Fe, Cu, Co and Zn). The bimetallic catalysts were prepared by the impregnation method and characterized by different analytical techniques. The catalyst performance for wet MSW gasification was evaluated in a fixed-bed reactor at optimized conditions (850°C and 50% moisture content of MSW). The results revealed that the addition of Ni-WMP catalyst greatly enhanced the dry gas yield (DGY), H2 yield, carbon conversion efficiency (CCE) and reduced the tar content from 0.73 to 1.16N.m3/kg, 212 to 509mL/g, 61.70% to 76.40% and 9.11 to 3.9wt%, respectively, compared to without catalyst. In contrast to the Ni-WMP catalyst, the transition metal promoted catalysts showed higher catalytic activity towards H2 yield (549-629mL/g), DGY (1.19-1.30N.m3/kg), and lower tar content (3.45-2.93wt%). The results revealed that Co promoted bimetallic catalyst performed better than Fe, Cu and Zn promoted catalysts. The tar content produced was also analyzed via GC-MS (gas chromatography-mass spectrometry) to understand the effect of different catalysts on tar composition. According to experimental results, the bimetallic promoted catalysts can be ranked as Ni-Co-WMP>Ni-Cu-WMP>Ni-Fe-WMP>Ni-Zn-WMP based on H2 yield and tar removal.

Effects of different catalysts on performance of self-bonded SiC refractories

The 3C–SiC whisker was catalytically synthesized with extended graphite and Si powder firing at 1573K using 1 wt% Fe, 3 wt% Co or 3 wt% Ni as catalysts, respectively. First-principles calculation results show the activities of the reactants of the synthesis of SiC could be increased via dwindling the bonding strength of CC, Si–O and C–O bonds. Furthermore, the performance of self-bonded SiC refractories prepared by the present catalytic method was enhanced including the mechanical properties (Fracture toughness of 1.35 MPa﹒m1/2 for the containing Fe catalysts samples, Fracture surface energy of 114 J﹒m−2 and MOR of 32.2 MPa (1473 K) for the sample with Ni catalysts), as well as the TSR (Residual MOR and Residual MOR percentage of 13.17 MPa and 62% at ΔT = 1075 K, respectively). The results indicate that the incorporation of catalysts decreased the reaction temperature by about 100 K as well as facilitated the in-situ formation of 3C–SiC whiskers, which interlinked and connected each other in the matrix of as-prepared self-bonded refractories and improved the high temperature properties. Among them, the Fe NPs presented the best catalytic activity.

Catalytic Sc(OTf)3 mediated direct asymmetric aldol reaction of (−)‐menthyl isothiocyanatoacetate with aldehydes by using (−)‐menthol as chiral auxiliary

AbstractThis method involves the direct asymmetric aldol reaction of (−)‐menthyl isothiocyanatoacetate 5 with a variety of substituted aromatic aldehydes, which offers a convenient method for the synthesis of intermediate containing biologically relevant α‐amino β‐hydroxyl groups in oxazolidine ring. In this methodology, the products show remarkable diastereoselectivity using Sc(OTf)3 as a catalyst and easily accessible (−)‐menthol as a chiral auxiliary. This approach includes some important aspects such as mild reaction conditions, high yields, and excellent diastereoselectivity with a number of substituted aromatic aldehydes. The optimization and effect of different catalysts were studied at different reaction conditions and it is found that Sc(OTf)3 shows excellent diastereoselectivity at −45°C.

Catalytic Regulation of Oligomers in Polycaprolactone

l Tetraphenyltin catalyst improved the performance of PCL l The obtained PCL showed the Mn 80000, PDI 1.36, and 4.251 wt.% oligomers l The formation and contents of oligomers in PCL was revealed l Coordination inserting an anhydride bond was the main mechanism for inhibiting the formation of oligomers There is a lack of effective approaches that produce polycaprolactone (PCL) materials with a high molecular weight, narrow polymer dispersity index (PDI), and fewer formations of oligomers. The immigration of the remained oligomers predominantly causes poor PCL quality and induces odor release. This study investigates the effects of different catalysts and loadings on the PCL performance along with the formation of oligomers in detail. The results show that tetraphenyltin is an effective catalyst to promote propagation and produce high-performance PCL that possesses the highest Mn (80000), narrowest PDI (1.36), and the lowest content of oligomers (4.251 wt.%). Density functional theory (DFT) studies combining with characterizing key intermediates verified that an anhydride bond was formed close to the end hydroxyl group in the PCL chain because of the particular mechanism. This unusual chemical structure effectively suppresses the “back-biting” behavior, which is helpful for lowering the content of oligomers. This study provides a scalable synthetic approach to creating high-performance polymers.

Gram Scale Synthesis of Dual-Responsive Dendritic Polyglycerol Sulfate as Drug Delivery System.

Biocompatible polymers with the ability to load and release a cargo at the site of action in a smart response to stimuli have attracted great attention in the field of drug delivery and cancer therapy. In this work, we synthesize a dual-responsive dendritic polyglycerol sulfate (DR-dPGS) drug delivery system by copolymerization of glycidol, ε-caprolactone and an epoxide monomer bearing a disulfide bond (SSG), followed by sulfation of terminal hydroxyl groups of the copolymer. The effect of different catalysts, including Lewis acids and organic bases, on the molecular weight, monomer content and polymer structure was investigated. The degradation of the polymer backbone was proven in presence of reducing agents and candida antarctica Lipase B (CALB) enzyme, which results in the cleavage of the disulfides and ester bonds, respectively. The hydrophobic anticancer drug Doxorubicin (DOX) was loaded in the polymer and the kinetic assessment showed an enhanced drug release with glutathione (GSH) or CALB as compared to controls and a synergistic effect of a combination of both stimuli. Cell uptake was studied by using confocal laser scanning microscopy with HeLa cells and showed the uptake of the Dox-loaded carriers and the release of the drug into the nucleus. Cytotoxicity tests with three different cancer cell lines showed good tolerability of the polymers of as high concentrations as 1 mg mL−1, while cancer cell growth was efficiently inhibited by DR-dPGS@Dox.

Effect of different catalysts on recovery and reuse of waste polyurethane rigid foam

The sharp increase of waste polyurethane rigid foam has caused great harm to the natural environment. Ethylene glycol (EG) and propylene glycol (PG) was the alcoholysis agents, and KOH and Zn3[Co(CN)6]2(DMC) were used as catalysts for alcoholysis of waste polyurethane rigid foam. Regenerated polyols were prepared. The effects of different catalysts on the infrared, viscosity and hydroxyl content of alcoholysis products were discussed. Regenerated polyurethane rigid foam was prepared from alcoholysis products and analyzed by compression strength, thermal conductivity, water absorption, scanning and thermogravimetry. The effects of different catalysts on the recycling of waste polyurethane rigid foam were studied. The experimental results show that DMC catalyst is more effective than KOH catalyst under the same conditions.The alcoholysis product of DMC system has lower viscosity and higher hydroxyl content, which is more suitable for the preparation of regenerated polyurethane rigid foam., The compressive strength of the prepared regenerated polyurethane rigid foam is 254 Kpa, and the thermal conductivity is 0.0213 W m−1·K−1 when the amount of DMC added is 0.04%. Meanwhile, the regenerated polyurethane rigid foam has good hydrophobicity, excellent heat preservation performance, complete cell morphology and good thermal stability. It can replace the traditional polyols to prepare the regenerated polyurethane material which meets the national standard ‘rigid polyurethane foam for building insulation’ (GB/ T21558-2005).

Catalytic thermochemical cracking of polyethylene over nanocomposite bentonite clay

Catalytic thermochemical cracking of polyethylene has been investigated in presence of a series of bentonite clay based nanocomposite with a view toward assessing their suitability in a process for converting plastic waste to fuel. Metal oxides such as manganese oxide (MnO), titanium oxide (TiO2) and zinc oxide (ZnO) were impregnated with sodium montomorillonite bentonite. The clay catalysts were characterized by x-ray diffraction (XRD), scan electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive x-ray (EDX) spectrometers. The effect of different catalysts on the composition and the yield of gaseous was evaluated. ZnO nanocomposite bentonite clay achieved the highest methane gas formation around 93%. The superior catalytic performance of nanocomposites is probably attributed to their uniform dispersed of oxides particles on montmorillonite support.

Enhanced photocatalytic performance of UiO-66-NH2/TiO2 composite for dye degradation.

In this study, the performance of TiO2, ZnO, UiO-66-NH2 and UiO-66-NH2/TiO2 nanoparticles was investigated. They apply as photocatalysts for the destruction of organic reactive red dye 120 (RR120) under UV light. In order to determine the optimal conditions, effects of different catalysts and initial dye concentration, H2O2 content and catalyst loading parameters were examined. Taguchi-designed experimental method was used to obtain optimal test conditions. The physical and chemical properties of synthetic photocatalysts were investigated by SEM, XRD, EDX, BET and DRS. SEM images show that the globular particles of titania are well placed on the surface of the metal-organic framework (MOF). XRD and EDX analyses also confirmed the presence of titania in the synthesised UiO-66-NH2/TiO2 photocatalyst. Optimal values of H2O2, pH, the amount of catalyst, the dye concentration and the type of available photocatalyst to remove the RR120 dye, were obtained by 80 μl/l, 3 mg/l, 5 mg/l and 20 mg/l, UiO-66-NH2/TiO2 catalyst, respectively. The required time for complete removal of RR120 dye under detection limit of 0.136 mg/l in optimal conditions was 10 min. The RR120 photocatalytic degradation followed the first-order kinetic equation according to the Langmuir-Hinshelwood model (kapp = 0.407 min-1). The result of optimisation showed the 20 wt% of the titania on MOF (UiO-66-NH2) photocatalyst can be used in advanced oxidation processes, and it can be used as a suitable option for cleaning coloured effluent.

Catalytic fast pyrolysis of low density polyethylene into naphtha with high selectivity by dual-catalyst tandem catalysis

In this work, catalytic fast pyrolysis of low density polyethylene (LDPE) into highly valuable naphtha by the relay catalysis (Al2O3 followed by ZSM-5 zeolite) was conducted. Effects of different catalysts, pyrolysis temperatures, catalyst to plastic ratio, and Al2O3 to ZSM-5 ratio, on product distribution and selectivity were studied. Al2O3 shows an excellent performance for catalytic reforming of LDPE pyrolysis vapors, mainly producing C5-C23 olefins that are the important precursors to form aromatics via Diels-Alder, aromatization, and polymerization reactions in the pores of ZSM-5 catalyst. Experimental results also show that the selectivity of monoaromatics and C5-C12 alkanes/olefins can be up to 100% over Al2O3 followed by ZSM-5 relay catalysis at the temperature of 550 °C, the catalyst to plastic ratio of 4:1, and Al2O3 to ZSM-5 ratio of 1:1. The product (monoaromatics and C5-C12 alkanes/olefins), naphtha, could be a renewable feedstock for new plastic production in the petroleum industry so that this finding might provide a new insight for a circular economy.

A review on factor affecting biodiesel production from waste cooking oil: An Indian perspective

In the present scenario fluctuating oil prices and disrupting energy demand and supply chain of the world makes an energy-intensive country like India which mostly depends on the oil and gas import from gulf countries to fulfill its energy needs, vulnerable to energy security. Biodiesel has emerged as a potential alternative to diesel, but its production on a large scale has barriers such as high production cost. Waste Cooking Oil emerges as a cheaper option to biodiesel feedstock, thus reducing overall biodiesel production cost relative to other feedstocks. Additionally, it solves the waste oil disposal problem. The main aim of this review paper is to discuss and highlight the effects of different catalysts and process intensification techniques on the yield of biodiesel derived from the waste cooking oil (WCO). This review paper also provides an overview of the Indian scenario in the context of the collection mechanism for waste cooking oil and its potential for biodiesel production.

Efficiently enhanced visible-light photocatalytic activity by in situ deposition of Ag@AgBr on g-C3N4/Fe3O4 magnetic heterogeneous materials

In this study, graphitic carbon nitride (g-C3N4) (CN) was conveniently and environmentally modified into a stable and easily recyclable photocatalyst for the high removal efficiency of dye contaminants in water. Magnetic carrier (CN/Fe3O4) and heterojunction photocatalysts (Ag@AgBr/CN/Fe3O4) were prepared by ultrasonic and in situ deposition of Fe3O4 and Ag@AgBr nanoparticles on the CN, respectively, and characterized by the surface structure, optical, and electrochemical properties. The effects of different catalysts, silver loading, catalyst dosage, and different aeration conditions on the photocatalytic degradation of RhB were investigated. Results exhibited that the removal rate of RhB by Ag@AgBr/CN/Fe3O4 reached 96% within 150 min when the Ag loading was 5%, the catalyst dosage was 0.4 g/L, and the aeration was air. Furthermore, the degradation rate constant was 17.3 × 10−3 min−1, which was 4.3 and 3.4 times higher than that of CN and CN/Fe3O4, respectively. The stability study demonstrated that Ag@AgBr/CN/Fe3O4 had almost no risk of Ag and Fe leakage and showed high stability. Mechanism study indicated that the construction of Z-scheme heterojunction between Ag@AgBr and CN and trapping electron by Fe3+ promoted charge transfer and electron–hole pair separation, thus enhancing photocatalytic activity.

Ex-situ catalytic fast pyrolysis of soapstock for aromatic oil over microwave-driven HZSM-5@SiC ceramic foam

In view of the poor selectivity of aromatic hydrocarbons in bio-oil from biomass pyrolysis and the high pressure drop and rapid coking and deactivation of catalyst in industrial scale, a microwave-driven HZSM-5@SiC ceramic foam has been constructed, and applied to the ex-situ catalytic fast pyrolysis of soapstock to improve the content of aromatic hydrocarbons in bio-oil. The effects of different catalysts and heating modes and mass ratios of HZSM-5@SiC ceramic foam to soapstock on the distribution of pyrolysis products have been investigated. In addition, combined with the comparison of microwave and electric heating, the deactivation characteristics of HZSM-5@SiC ceramic foam have been studied. Finally, the process of preparing aromatic oil by microwave-driven catalytic pyrolysis of soapstock was discussed. Experimental results indicate that compared with HZSM-5, HZSM-5@SiC ceramic foam has a higher yield of bio-oil and higher aromatization activity. Under microwave heating, the relative content of aromatic hydrocarbons increases from 25.18% to 100% when the mass ratio of HZSM-5@SiC ceramic foam to soapstock increases from 0:1 to 1:1. Compared with electric heating catalysis, HZSM-5@SiC ceramic foam has the lowest yield of coke under microwave heating. After five consecutive uses, it still maintains more than 90% catalytic activity and has higher stability, which provides a scientific basis for the pilot scale experiments of soapstock catalytic pyrolysis.

Valorization of sewage sludge through catalytic sub- and supercritical water gasification

Sub- and supercritical water gasification is applied to recover energy from sewage sludge in a batch reactor. The effects of reaction temperature and water-soluble additives as catalysts on gasification were examined. The resultant products, including syngas, hydrochar and liquid residues were characterized. The rise of temperature without the presence of catalysts increased the yield of H2 (0.06 (350 °C) to 1.91 mol/kg (450 °C) and enhanced the gasification efficiency (1.29–19.61%), and decreased total organic carbon (TOC) by 68.50% in liquid residue. The changes in product distribution and characteristics of hydrochar and liquid residue implied that the organic matters in sewage sludge were dissolved and hydrolyzed in sub- and supercritical water, resulting in the production of syngas. The catalytic effect of different catalysts in relation to the H2 gas yield was in the following order: KOH > NaOH > Na2CO3 ≈ K2CO3. In the case of catalytic supercritical water gasification at 400 °C, the highest molar fraction (37.28%) and yield of H2 (1.60 mol/kg) were obtained in the presence of KOH. Furthermore, the scanning electron microscopy (SEM) analysis indicated that a conversion and dissolution of the organic matters in sewage sludge to liquid and gas, produced a porous, fragmented structure and disintegrated surface of hydrochar.