Increase In Amount Of Catalyst Research Articles

Production of valuable chemicals through the catalytic pyrolysis of harmful oil sludge over metal-loaded HZSM-5 catalysts

This research studied the catalytic pyrolysis of oil sludge (OS) over metal-loaded HZSM-5 catalysts, an eco-friendly and cost-effective technology to produce value-added aromatics such as benzene, toluene, ethylbenzene, and xylene (BTEXs). In particular, it evaluated the respective effects of the experimental parameters: the type and amount of the metal loaded, the reaction temperature, and the OS/catalyst ratio, on the BTEXs yield sequentially to achieve optimum conditions. This evaluation showed that the highest yields of the BTEXs (6.61 wt%) and other aromatics were achieved when Ni was incorporated into the HZSM-5 (Ni/HZSM-5) followed by the corresponding yields of Ga/HZSM-5 and Fe/HZSM-5, due to a better distribution of Ni on the support surface and an enhanced acidity strength of this catalyst. Further, increase in Ni loading (up to 10 wt% Ni/HZSM-5) increased the BTEXs yield to 13.48 wt%. However, the excessive Ni loading (15 wt% Ni/HZSM-5) resulted in a reduced BTEXs yield due to the blockage of the zeolite channels. Next, an increase in the reaction temperature from 500 °C to 600 °C increased the yield of the BTEXs and other aromatics. However, a further increase in the reaction temperature to 650 °C decreased slightly their yield because of the stimulating secondary reactions at high temperatures. The increase of catalyst amount (OS/catalyst of 1/3) also maximized the BTEXs yield (30.50 wt%).

Study on supercritical water gasification reaction and kinetic of coal model compounds

Supercritical water gasification (SCWG) of coal is a clean coal utilization technology that has gradually developed in recent years. It has great application prospect because of low pollution, good economy and high energy efficiency. Due to the complexity of coal molecular structure, it is difficult to directly study SCWG mechanism of coal at molecular level. Based on the Wiser molecular structure model of coal, diphenyl ether and diphenylmethane were selected as model compounds to study the bond breaking characteristics and gasification law of characteristic bridge bonds. The effects of catalyst, temperature, concentration and other factors on model compounds gasification were discussed. The results showed that temperature had the most significant influence on gasification effect. The effect order of catalyst on promoting gasification from high to low was: K2CO3 > Na2CO3 > Ca(OH)2. The increase of catalyst amount and residence time had a certain promotion effect on gasification reaction. Under the same condition, the gasification effect of diphenyl ether was better than that of diphenylmethane. At the same time, the kinetic model of coal-like structure model compound gasification in SCW was established, and the key parameters were solved. The activation energy of diphenyl ether and diphenylmethane was 82.96 kJ/mol and 99.92 kJ/mol, respectively.

Optimization of Synthesis of Ethyl Acetate by Response Surface Method and Investigation of Reactive Sorption Effect of Hydrogel in Synthesis

In this study, ethyl acetate synthesis is made from ethyl alcohol and acetic acid. Ethyl acetate is used as solvent and alternative fuel additive The synthesis was optimized by the surface response method. The effects of temperature, catalyst amount and reactant initial molar ratio on acid conversion in the reaction were investigated. Sulfo succinic acid was used as the catalyst. Conversion values were increased with increase in initial molar ratio, increase in catalyst amount, and increase in temperature. In this study, poly vinyl alcohol hydrogels were also prepared for reactive sorption application. Hydrogels were added to the reactor under certain operating conditions and used in the esterification reaction. It was observed that the conversion increased by using hydrogels together with catalyst. Ethyl acetate synthesis was optimized by using the student version of the Design Expert software. Optimization was made with the center composite design method by using response surface method. Quadratic model is proposed by the program. Experimental data and model data were found compatible with each other. Optimum values for conversion are variables that the temperature is 80 °C, the amount of catalyst is 1% and the initial molar ratio is 5. The highest conversion value of 89.35% could be achieved by the optimum values.

Experimental and numerical investigation of catalytic PM combustion in a fluidized bed type PM removal device for low-temperature continuous regeneration

A fluidized bed filter can perform highly efficient PM collection and low-temperature continuous regeneration. However, to further reduce continuous regeneration temperature, a rough surface bed particle was selected herein. It is expected that the rough surface increases and stabilizes doped catalyst on bed particle even in fluidized bed. This bed particle can stably support 9.48 g-catalyst/kg-bed particle of doped catalyst versus 1.58 g-catalyst/kg-bed particle in previous research. This increase in catalyst amount increases the probability of good PM-catalyst contact, and collection efficiency can easily maintain its initial value due to catalytic PM combustion. PM combustion also depends on fluidization. Thus, combustion kinetics in a fluidized bed was investigated via a newly developed thermogravimetric analyzer that considered PM-gas relative velocity, and a constructed kinetic model was applied to numerical simulation. PM combustion obeyed an Arrhenius relationship, and the effect of PM-gas relative velocity was included in the kinetic model as a mass transfer term. A continuous regeneration experiment was conducted under optimal conditions, and the continuous regeneration temperature is 330 °C. As water vapor occurs in combustor exhaust, we added 10 vol% water vapor and found that the continuous regeneration is further reduced to 300 °C.

Effect of Potassium Carbonate Catalyst on Pyrolysis of Milicia excelsa in a Fixed Bed Reactor

The effect of potassium carbonate catalyst on the products distribution from pyrolysis of Milicia excelsa (Iroko) at various temperatures (400, 500 and 600 oC) was investigated. Milicia excelsa sawdust was obtained from a sawmill in Ogbomoso, South-Western Nigeria and was sundried for five days in order to reduce its moisture content. Catalytic pyrolysis of the sawdust was performed with different amounts of catalyst (10, 20, 30 and 40 wt.%). Non-catalytic pyrolysis was also performed for the same temperatures and the products distributions from both batches were compared. Char yield generally increased with increase in catalyst amount for all the temperatures considered. Tar yield did not follow any definite pattern with increasing amount of catalyst as different trends were obtained for different temperatures. Gas yield generally decreased with increase in catalyst amount in the feed. Char yields from non-catalytic experiments were higher than those obtained from catalytic runs, with the highest value of 68% at 400 oC. Tar yields from catalytic pyrolysis were higher than those from non-catalytic process at 400 oC (biomass/catalyst ratio of 90/10) and at 500 oC (biomass/catalyst ratios of 70/70 and 60/40), the highest yield being 29.47% at 500 oC and biomass/catalyst ratio of 60/40. Gas yields from catalytic pyrolysis were higher than those from non-catalytic runs except at 500 oC (biomass/catalyst ratio of 60/40), the highest being 51.3% at 600 oC (biomass/catalyst ratio of 90/10). By making use of appropriate biomass/catalyst ratio and temperature, the yield of liquid fuel from catalytic pyrolysis of Milicia excelsa can be increased.Keywords— Catalyst, potassium carbonate, pyrolysis, biomass, product distribution

Heterogeneous sonocatalytic degradation of Bisphenol-A and the influence of the reaction parameters and ultrasonic frequency.

In the present study, the sonocatalytic oxidation of Bisphenol-A (BPA) was investigated in the presence of a LaFeO3 perovskite catalyst. The effects of the reaction temperature, initial pH, catalyst loading, presence of inorganic anions and sonication source (power and frequency) on the removal of BPA using heterogeneous sonocatalytic process were investigated. Under the studied temperature range of 288-318 K, 308 K was selected as the optimum temperature and the highest BPA removal and total oxygen demand (TOC) reduction of, 95.8% and 30.4% were achieved at that temperature. The thermodynamic parameters were calculated in the studied temperature range of 288-308 K. It was seen that an acidic pH of 3.0 was favorable for the BPA oxidation with the highest BPA removal and TOC reduction of 95.4% and 31.5%, respectively. Doubling the catalyst amount from 0.25 g/L to 0.5 g/L increased the BPA removal degree from 81.6% to 90.8%. However, further increase in catalyst amount has no remarkable positive effect on the removal of BPA. The removal of BPA was described by the first order kinetics with an activation energy of 14.9 kJ/mol. The results obtained from this study showed that the LaFeO3 perovskite catalyst was a good sonocatalyst giving high oxidation rates of BPA.

An investigation on electroless nickel coating on yttria stabilized zirconia nanoparticles via single step surface activation methods

Metal coated ceramic nanopowders have a considerable potential for many fields of applications. Here, electroless coating of pure nickel onto yttria-stabilized zirconia nanoparticles is studied. We introduce a single step method to activate ceramic nanoparticles surface to reduce complexities of electroless coating on ceramic nanoparticles by conventional double step pre-treatments. X-ray diffraction and electron diffraction patterns beside transmission electron microscopy images are used to analyze the coated nanoparticles. We observe that palladium hydroxide acts as a catalyst for electroless nickel reaction like palladium and the ceramic nanopowders surface is effectively activated for electroless reaction by simpler single step activation methods. Atomic absorption spectroscopy results show that the performance of electroless reaction is not enhanced by increase in catalyst amount. Also, relative changes in amount of deposited nickel are investigated via magnetization curves of the coated particles. The vibrating sample magnetometery results demonstrate the magnetic behavior of the processed particles can be modified by deposited nickel amount.

Waste to wealth: conversion of nano‐magnetic eggshell (Fe3O4@Eggshell) to Fe3O4@Ca(HSO4)2: cheap, green and environment‐friendly solid acid catalyst

Eggshell is a hazardous waste by European Union regulations, so that discarded thousands of tons per year. To convert waste (eggshell) to wealth (catalyst), nano‐magnetic eggshell was prepared based on the nano‐Fe3O4, and then the eggshell was converted to Ca(HSO4)2 with organic acid, namely, chlorosulfonic acid. Based on the back titration, 5.18 mmol SO4H group was loaded per gram of the nano‐structure. Using this method eggshell was converted to cheap, green and environment‐friendly solid acid catalyst. The prepared catalyst (nano‐ Fe3O4@Ca(HSO4)2) was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), energy dispersive X‐ray spectroscopy (EDX), field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and thermal gravimetric analysis (TGA). The activity of eggshell waste‐derived catalysts was successfully evaluated in the synthesis of value‐added products, namely indazolo[1,2‐b]‐phthalazinetrione derivatives as a benchmark multicomponent reaction. In addition, design of experiments shows that increase in amount of catalyst (and temperature), boost the reaction yield, especially with steeper slope at higher temperature.

Optimization of Catalytic Glycerol Etherification with Ethanol in a Continuous Reactor

In the past few decades, biodiesel has emerged as a promising renewable energy source. However, its production usually leads to the formation of large amounts of glycerol as a byproduct. This article reports the evaluation of catalytic glycerol etherification with ethanol over a series of catalysts in a continuous reactor. Amberlyst 15 presented the best performance in terms of glycerol conversion and yield of ethers. This result was attributed to its high pore size and acidity. Beta zeolite (Si/Al = 12.5) and niobic acid, both with lower acid strengths and pore sizes, were almost inactive in the conversion of glycerol into ethers. A central composite design was developed to optimize the performance of Amberlyst 15. An increase in catalyst amount enhanced both the glycerol conversion and the yield of ethers. However, high temperatures and low molar ratios favored side reactions. The optimized value for glycerol conversion was 91%, and that for the yield of ethers was 13%, under different reaction conditions.

Steam reforming of phenol as biomass tar model compound over Ni/Al2O3 catalyst

Catalytic steam reforming of phenol over Ni/Al2O3 catalyst with 10wt% of Ni loading was carried out in a fixed bed reactor. The effect of temperature (650–800°C), reaction time (20–80min) and catalyst amount (0–2g corresponding to 0–4.5gcathgphenol−1) on carbon conversion, H2 potential and catalyst deactivation was studied. High efficiency of Ni/Al2O3 catalyst in steam reforming of phenol is observed at 750°C for a reaction time of 60min when 1.5g of catalyst (3.4gcathgphenol−1) is used, with carbon conversion and H2 potential being 81 and 59%, respectively. An increase in temperature enhances phenol reforming reaction as well as coke gasification, minimizing its deposition over the catalyst. However, at high temperatures (800°C) an increase in Ni crystal size is observed indicating catalyst irreversible deactivation by sintering. As catalyst time on stream is increased the coke amount deposited over the catalyst increases, but no differences in Ni crystal size are observed. An increase in catalyst amount from 0 to 1.5g increases H2 potential, but no further improvement is observed above 1.5g. It is not observed significant catalyst deactivation by coke deposition, with the coke amount deposited over the catalyst being lower than 5% in all the runs.

Ultrasound enhanced heterogeneous activation of peroxydisulfate by bimetallic Fe-Co/GAC catalyst for the degradation of Acid Orange 7 in water

Bimetallic Fe-Co/GAC (granular activated carbon) was prepared and used as heterogeneous catalyst in the ultrasound enhanced heterogeneous activation of peroxydisulfate (PS, S2O2−8) process. The effect of initial pH, PS concentration, catalyst addition and stirring rate on the decolorization of Acid Orange 7 (AO7) was investigated. The results showed that the decolorization efficiency increased with an increase in PS concentration from 0.3 to 0.5 g/L and an increase in catalyst amount from 0.5 to 0.8 g/L. But further increase in PS concentration and catalyst addition would result in an unpronounced increase in decolorization efficiency. In the range of 300 to 900 r/min, stirring rate had little effect on AO7 decolorization. The catalyst stability was evaluated by measuring decolorization efficiency for four successive cycles.

Oscillatory behavior of the H2–SCR over Pt/HY

Oscillatory behavior of the selective catalytic reduction of NOx by hydrogen (H2–SCR) was studied over Pt/HY catalyst. It was found that the oscillation frequency increases with the increase of catalyst amount, reaction temperature and the H2 concentration in the feed gas within the range of tested experimental conditions. The NOx-TPD indicates that the adsorption–desorption of NOx on Pt particles is involved in the oscillation. It is proposed that the primary surface species on the Pt particle is alternatively changed between Pt–NOx and Pt–H, and the oscillatory behavior of the H2–SCR is a statistic result of oscillations on many Pt particles. The in situ FTIR and NH3 pulse injection studies reveal that NH3 is involved in the synchronous oscillation.

Selective hydrogenation of cinnamaldehyde over ZSM-5 supported Co catalysts

ZSM-5 supported Co catalysts were synthesized for the selective reduction of cinnamaldehyde (CMA) to the corresponding cinnamyl alcohol (CMO). The effects of the support (ratio of Si/Al of ZSM-5), catalysts pre-treatment (calcination) and catalyst amount on the conversion of CMA and selectivity to CMO were studied. The results showed that a lower ratio of Si/Al showed higher activity and the catalyst exhibited the highest yield of CMO when the ratio of Si/Al for ZSM-5 was 25. The conversion of CMA increased with the increase of catalyst amount. The reaction results showed that the highest activity occurred when the calcination temperature was 873 K, and the optimum CMO yield was obtained from the catalyst calcined at 773 K. The optimum CMO yield (61.9 %) obtained from Co/ZSM-5(25) catalyst (0.6 g) after reaction for 6 h.

Synergy of adsorption and visible light photocatalysis to decolor methyl orange by activated carbon/nanosized CdS/chitosan composite

Activated carbon/nanosized CdS/chitosan (AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature (≤60 °C) and ambient pressure. Methyl orange (MO) was chosen as a model pollutant to evaluate synergistic effect of adsorption and photocatalytic decolorization by this innovative photocatalyst under visible light irradiation. Effects of various parameters such as catalyst amount, initial MO concentration, solution pH and reuse of catalyst on the decolorization of MO were investigated to optimize operational conditions. The decolorization of MO catalyzed by AC/n-CdS/CS fits the Langmuir-Hinshelwood kinetics model, and a surface reaction, where the dyes are absorbed, is the controlling step of the process. Decolorization efficiency of MO is improved with the increase in catalyst amount within a certain range. The photodecolorization of MO is more efficient in acidic media than alkaline media. The decolorization efficiency of MO is still higher than 84% after five cycles and 60 min under visible light irradiation, which confirms the reusability of AC/n-CdS/CS composite catalyst.

Photocatalytic Activities of Bi2O3, WO3, and Fe2O3: An Assessment through Decomposition of Peroxomonosulfate in Visible Radiation

Abstract Bi2O3 semiconductor powder (Eg=2.8–2.9 eV) was chosen for the first time to effect photocatalysis and was found to decompose peroxomonosulfate (PMS) with visible light of λ>400 nm. Doping of Bi2O3 with Cu(II)-ion considerably enhanced the photocatalytic efficiency. The effects of variation of (i) the [dopant] in Cu(II)/Bi2O3, (ii) the catalyst amount, and (iii) the initial [PMS] on the rate of decomposition of PMS were investigated. It was observed that (a) 4 atomic % was the optimum [dopant] for Cu(II)/Bi2C3, (b) the rate increased linearly with increase in catalyst amount, and (c) the decomposition of PMS followed a Langmuir kinetics in the concentration range, [PMS]0=0.5–3.0×10−3 mol dm−3. A suitable reaction mechanism is proposed for the decomposition of PMS involving all the possible reactions. A comparative analysis of the photocatalytic activities of undoped and Cu(II)-doped Bi2O3, WO3, and Fe2O3 indicated that Cu(II)-doping enhances the activity of Bi2O3 to a greater extent than those observed with the other two semiconductors. This photocatalytic decomposition of PMS is one of the examples of visible light assisted reaction which otherwise takes place under UV radiation (λ≤280 nm) only.

Some characteristics of the telomerization of propylene with CCl4, catalyzed by fecl3 or by the system: FeCl3-Solvent

1. A study was made of the dependence of the distribution of the telomer homologs and the initial rates for the telomerization of propylene with CCl4 in the presence of various amounts of FeCl3 on the concentrations of the components of the FeCl3-solvent system at 145°. 2. The reaction rate and the relative yield of the adduct both increased with increase in the initial amount of catalyst. A complete suppression of the telomerization and an acceleration of the process were observed when certain donor solvents were added. A proposed mechanism for the catalytic action of the iron salt and the effect of the nature of the solvent on the activity of the catalyst are discussed.

Catalytic Action of Transition Metal Carbonyl. I

Authors investigated the catalytic behavior of iron pentacarbonyl in the hydrogenation of C-C double bond. Each 30 g of cotton seed oil was reacted with 1.2 or 2.4 g of iron-pentacarbonyl in the following reaction conditions ; initial hydrogen pressure : 25 or 50 kg/cm2, temperature : 180 or 200°C and time : 2 or 4 hr.From the statistical consideration of the relations between reaction conditions and the composition of reaction products authors recognized the selectivity of hydrogenation between linoleic acid and oleic acid, namely, higher temperature and smaller quantity of catalyst were favourable to the selective formation of oleic acid, on the other hand higher temperature, higher hydrogen pressure and increase in amount of catalyst accelerated the stearic acid formation. As the side reactions the formation of high boiling substance and an iron-carbonyl complex compound were also detected. The former is considered as dimer of linoleic acid, and was preponderately produced in the case of lower temperature and more catalyst. The latter was revealed to be conjugated linoleic acid iron-tricarbonyl.Experimental results suggest the following reaction mechanism : -A certain labile complex compound such as monoene-iron-tetracarbonyl is formed at first from linoleic acid. If iron-pentacarbonyl is present in a larger amount, such intermediate is also formed from oleic acid. In the next step of hydrogencracking, oleic acid or stearic acid is formed from each of their respective intermediates. The intermediate, formed from linoleic acid, is simultaneously converted into comparatively stable type of diene iron-tricarbonyl, which can be also produced directly through the conjugation reaction of linoleic acid followed by complex formation reaction. In the excess thermal treatment this compound is decomposed and converted into dimer, on this occasion the iron-carbonyl residue of transition state may also act as the catalyst for dimerization.