PRODUCTION OF BIOFUEL FROM SOFT SHELL OF PISTACHIO (PISTACIA VERA L.)

Soft shell of pistachio (Pistacia vera L.) pyrolysis experiments were performed in a fixed-bed reactor to produce bio-oil. The effects of temperature, heating rate, and sweep gas (N₂) flow rates on the yields and compositions of products were investigated. Pyrolysis runs were performed using reactor temperatures between 350° and 500°C with heating rates of 15° and 50°C/min. Nitrogen flow rates varied between 50 and 200 cm³/min and mean particle size was 0.8 mm. The maximum bio-oil yield of 33.18% was obtained in a nitrogen atmosphere with nitrogen flow rate of 150 cm³/min and at 450°C pyrolysis temperature with a heating rate of 50°C/min.The elemental analysis and gross heating value of the bio-oil were determined, and then the chemical composition of the bio-oil was investigated using chromatographic and spectroscopic techniques. The chemical characterization has shown that the bio-oil obtained from soft shell of pistachio can be used as a renewable fuel and chemical feedstock.     

Pyrolysis of rapeseed in a free fall reactor for production of bio-oil

Pyrolysis experiments of rapeseed (Brassica napus L.) were performed in a free fall reactor at atmospheric pressure under nitrogen atmosphere. The effects of final pyrolysis temperature, particle size and sweep gas flow rate on the yields of products were investigated. The temperature of pyrolysis, particle size and sweep gas flow rate were varied in the ranges of 400—700 °C, −0.224 to 1.8 mm and 50–400 cm³ min⁻¹, respectively. The elemental analysis and calorific value of the bio-oil were determined, and compared with diesel fuel and then the chemical composition of the bio-oil was investigated using chromatographic and spectroscopic techniques (¹H NMR, IR, column chromatography and GC/MS). The chemical characterization has shown that the bio-oil obtained from rapeseed could be use as diesel fuel and chemical feeedstock.     

A study of the properties of pyrolytic carbons deposited from propane in a tumbling and stationary bed between 900 and 1230°C

In order to obtain low-temperature-isotropic (LTI) pyrolytic carbons, a new “Tumbling Bed” reactor has been developed. The characteristics of the pyrolytic carbons deposited in this tumbling bed have been studied by varying the gas composition, the total gas flow rate, the weight of bed particles and the rotational speed (RPM) of the reaction tube in the temperature range of 900–1230°C. It was found that all pyrolytic carbons deposited were isotropic in the temperature range of 1050–1230°C. The density of the Isotropie carbon increased slightly with temperature, but it was independent of the other variables with values of 1.9–2.0 g/cm³. The apparent crystallite size, L_e, of the isotropic carbon was about 30 Å regardless of coating conditions. The deposition rate increased with temperature, propane concentration, and total flow rate, showed a minimum with increasing RPM of reaction tube, and decreased with the weight of bed particles. The deposition mechanism of the isotropic pyrolytic carbon was suggested from the results. Additionally, a few experiments were carried out in a stationary bed in order to study the role of the rotating action in the tumbling bed reactor. Columnar, sooty and filamentous carbons were obtained in the stationary bed. From scanning electron micrographs of fracture surfaces of the filamentous carbons, it appeared that they are constructed by spiral growth of carbon flakes.     

Thermogravimetric characteristics of <Emphasis Type="Italic">α</Emphasis>-cellulose and decomposition kinetics in a micro-tubing reactor

The pyrolysis characteristics and kinetics of α-cellulose were investigated using thermogravimetric analyzer (TGA) and micro tubing reactor, respectively. Most of the α-cellulose decomposed between 250 and 400 °C at heating rate of 5–20 °C/min. The apparent activation energy was observed in the range of 263.02 kJ mol^?1 to 306.21 kJ mol^?1 at the conversion of 10-80%. The kinetic parameters were determined by nonlinear least-squares regression of the experimental data, assuming first-order kinetics. It was found from the kinetic rate constants that the predominant reaction pathway was A(α-cellulose) to B(bio-oil) rather than A(α-cellulose) to C(gas; C₁-C₄) and/or to B(bio-oil) to C(gas; C₁-C₄) at temperatures of 340-360 °C.     

Isomerization of α-pinene to camphene

The catalytic isomerization reaction of α-pinene to camphene over a clinoptilolite catalyst was investigated in a batch reactor open to the atmosphere between 130 and 155°C. The catalyst was selective to the isomerization of α-pinene to camphene. The effects of several variables, such as reaction temperature, amount of catalyst, stirring speed and catalyst particle size, on the conversion of α-pinene and selectivity to camphene were determined. The reaction fits a first-order parallel reaction with rate constants of k ₁ = 3.020·10^?2 e ^?33381.6/RT for the production of camphene and of k ₂ = 1.576·10^?2 e ^?31096.53/RT for the production of limonene.     

Polymerisation von Vinylchlorid bei Atmosphärendruck 1. Polymerisationssysteme zur Herstellung von U-PVC

A method for polymerization of vinylchloride (VC) at atmospheric pressure is described, in which the gaseous monomer is polymerized with K₂S₂O₈ as an initiator at 45°C to 60°C. The amount of the polymer formed (so-called U-PVC) as a function of the reaction time depends on the rate of monomer flow. The reaction rate increases with higher initiator concentration as well as with increasing temperature. It is also possible to initiate the polymerization with the redox-system K₂S₂O₈/Na₂SO₃/Cu²⁺ within the range of 0°C to 20°C. By means of transmission electronmicroscopic (TEM) investigations the particle size and particle size distribution as a function of polymerization time and temperature was determined.     

Evaluation of two different scrap tires as hydrocarbon source by pyrolysis

The main objective of the present study is to investigate the effect of the polymer types in scrap tires on the pyrolysis products. Two different types of scrap tires (passenger car tire, PCT and truck tire, TT) have been pyrolyzed in a fixed bed reactor at the temperatures of 550, 650 and 800 °C under N₂ atmosphere. Pyrolysis products (gas, oil and carbon black) obtained from PCT and TT were investigated comparatively. The gaseous products were analyzed by GC–TCD. The psychical and chemical properties of pyrolytic oils were characterized by means of GC–FID, GC–MS, ¹H NMR. In addition, boiling point distributions of hydrocarbons in pyrolytic oils were determined by using simulated distillation curves in comparison with commercial diesel fuel. The production of activated carbon from pyrolytic carbon blacks (CBp) was also carried out. The composition of gaseous products from pyrolysis of PCT and TT were similar and they contained mainly hydrocarbons (C₁–C₄). Pyrolytic oils were found lighter than diesel but heavier than naphtha. The physical properties of pyrolytic oils from PCT and TT were similar at the same temperature. However, the composition of aromatic and sulphur content from pyrolysis of PCT was higher than that of TT. Furthermore, TT derived pyrolytic carbon black was found more suitable for the production of activated carbon due to its low ash content.     

Hydrodesulfurization of athabasca fluid coke — conversion and mechanism

Hydrodesulfurization of Athabasca (Syncrude) fluid coke was studied for particle sizes of ?74 + 53, ?53 + 44 and ?44 μm using a quartz reactor. Five flow rates of hydrogen from 1.2 × 10^?6 to 2.5 × 10^?6 m³/s were investigated with from 0.45 to 1.0 g of coke. Gas production — time profiles for H₂S and CH₄ were obtained at temperatures from 973 to 1073 K for each particle size range. Desulfurization rates were functions of particle size and temperature. Results agree with predictions of the shrinking core model, the rate being controlled initially by the gas film and chemical reaction resistances followed by control due to diffusion of hydrogen through the increasing ash layer. Below 998 K, the apparent activation energy was determined to be 293 kJ/mol · K, while at temperatures between 998 and 1073 K it was 29 kJ/mol · K.     

Effects of temperature,reaction time,atmosphere, and catalyst on hydrothermal liquefaction of Chlorella

Hydrothermal liquefaction (HTL) is the direct conversion of wet biomass into bio-oil at high temperature (200–400°C) and high pressure (10–25 MPa). In this work, we investigated HTL with 4.5 g of Chlorella and 45 ml of water/ethanol (1:1 vol. ratio) in a 100 ml reactor. Bio-oils produced are characterized via elemental analysis, thermogravimetric analysis, and gas chromatography–mass spectrometry (GC–MS). HTL of Chlorella was investigated at 240 and 250°C for 0 and 15 min under an air or H₂ atmosphere and with and without 5% zeolite Y. Temperature increased the bio-oil yield from 38.75% at 240°C to 43.04% at 250°C for 15 min reaction time. Longer reaction time increased the bio-oil yield at 250°C from 39.14% for 0 min to 43.04% for 15 min. The H₂ atmosphere had a significant effect for HTL at 240°C. Zeolite Y increased the bio-oil yield significantly from 32.03% to 43.06% at 250°C for 0 min. The carbon content of bio-oil increased with the temperature while the oxygen content decreased. The boiling point distribution of bio-oils in the range of 110–300°C varies with temperature, and atmosphere. At 240°C for 15 min, the 110–300°C range increased from 31.19% in air (240-15-air) to 39.25% in H₂ (240-15-H₂). The H₂ atmosphere increased the content of hydrocarbons, alcohols, and esters from 69.61% in air (240-0-air) to 82.83% in H₂ (240-0-H₂). Overall, temperature, reaction time, atmosphere, and catalyst all significantly influenced the yield and/or quality of bio-oils from HTL of Chlorella.     

The role of multiple gas—solid collisions in the catalytic decomposition of formic acid

An improved version of a low pressure free-molecular flow reactor is described. Use of a macroscopic, geometrically well-defined analog of a catalyst pore enables one to combine the multiple gas—solid collision effects of a high pressure supported catalyst with the detailed flow characterization available in a vacuum system. Simulations of the molecular trajectories within the reactor produce a relationship between an observed integral conversion and the probability of reaction when a gas molecule strikes the surface; low reaction probabilities are integrated experimentally in a manner which makes them readily observable. The Pt and Cu catalysed decomposition of formic acid was studied in two different reactor geometries at temperatures between 300°C and 450°C. The probability of reaction per collision on these surfaces was found to be independent of the collisional history and could be described by the relationships:Pr = 1.12 × 10⁴ exp (? 16000/R_gT) (platinum)Pr = 2.52 × 10⁵ exp (? 21600/R_gT) (copper). These probabilities are consistent with single collision experiments performed on various crystals and wires if the accommodation coefficient for the single collision is less than unity. No information on the molecular mechanism of decomposition was obtained.     

Manufacture of Granular Polysilicon from Trichlorosilane in a Fluidized‐Bed Reactor

Manufacturing of polysilicon by chemical vapor deposition from SiHCl₃ in a fluidized‐bed reactor was studied. The effects of reaction temperature, H₂/SiHCl₃ ratio, gas velocity, and seed particle loading were evaluated. The outlet gas composition was analyzed by gas chromatography. The physical features of the product particles were determined by scanning electron microscopy and laser particle size analyzer. Well‐grown product particles were obtained. The temperature and H₂/SiHCl₃ ratio significantly affected conversion, yield, and selectivity, which were less affected by gas velocity and seed particle loading at higher temperatures. The surface reaction kinetics determined the product yield only at lower temperatures, and thermodynamic equilibrium was approached at temperatures above 900 °C.     

Chemical modification of PVC by different nucleophiles in solvent/non-solvent system at high temperature

Chemical modification of polyvinyl chloride by nucleophiles is a versatile method for preparation of new functional polymers. Modification of PVC was carried out using different nucleophiles (Nu) in ethylene glycol (EG)/N,N-dimethylformamide (DMF) (1:1 by volume) solution. OH^?, N₃^?, and SCN^? were examined as nucleophiles in this study. The FTIR spectrum confirmed substitution of Cl by nucleophiles and also the elimination of HCl in the modification reaction of PVC. The glass transition temperatures (T_gs) of modified-PVC samples were in the order N₃^? > SCN^? > OH^? and were equal to 87.6, 86.8 and 78.15 °C, respectively. The T_5% (the temperature at which weight loss is 5%) of PVC was 266 °C, while after 1 h modification by OH^? it reduced to 197 °C. After alkaline modification, the scanning electron microscopy (SEM) images not only showed an increase in surface roughness and porosity, but also revealed a relatively large drop in average particle size from 160 to 80 µm. Molecular weight and molecular weight distribution were determined by gel permeation chromatography (GPC). The GPC results showed that the number average molecular weight (M_n) and weight average molecular weight (M_w) were decreased from 79,950 and 176,360 g mol^?1 in crude PVC to 45,370 and 99,930 g mol^?1, respectively, after 1 h modification by OH^?. Alkaline treatment also decreased the mechanical strength of PVC.     

A kinetic study of the isothermal degradation process of Lexan® using the conventional and Weibull kinetic analysis

The degradation process of commercial grade Lexan® was investigated by thermogravimetric technique under isothermal experimental conditions at four different operating temperatures: 375 °C, 387.5 °C, 400 °C and 425 °C. The kinetic triplet (E _a , A, f(α)) was determined using conventional and Weibull kinetic analysis. The applied kinetic procedure shows that the investigated degradation process can be described by two-parameter autocatalytic ?esták–Berggren (SB) reaction model. It was established that the degradation process of Lexan® can be described by the following kinetic triplet: E _a? =?158.3 kJ mol^?1, A?=?8.80?×?10⁹ min^?1 and f(α)?=?α ^0.33 (1???α)^1.62. It was established that the operating temperature has an influence on the values of SB reaction orders (m and n) (0.27?m?n??1, represent the composite value from a complex degradation reaction and can not compare with the dissociation energy of the weak bonds in bisphenol-A polycarbonate. Also, it was concluded that the Weibull shape parameter (β) shows that the considered process occurs under the same reaction mechanism, independently on operating temperature (T), i.e. the change of rate-limiting step does not occur (β?ddf) of apparent activation energies for considered degradation process. On the other hand, it was shown that the experimentally evaluated density distribution function of apparent activation energies represents the intermediate case between the calculated density distribution functions at 375 °C and 425 °C.     

Analysis of iron particle growth in aerosol reactor by a discrete-sectional model

The growth of iron particles by thermal decomposition of Fe(CO)₅ in a tubular reactor was analyzed by using a one dimensional discrete-sectional model with the coalescence by sintering of neighboring particles incorporated in. A thermal decomposition of Fe(CO)₅ vapor to produce iron particles was carried out at reactor temperatures varying from 300 to 1,000°C, and the effect of reactor temperature on particle size was compared with model prediction. The prediction exhibited good agreement with experimental observation that the primary particle size of iron was the largest at an intermediate temperature of 800°C. Model prediction was also compared with Giesen et al.’s [1] experimental data on iron particle production from Fe(CO)₅. Good agreement was shown in primary particle size, but a considerable deviation was observed in primary particle size distribution. The deviation may be due to an inadequate understanding of the sintering mechanism for the particles within an agglomerate and to the assumption of an ideal plug flow in model reactor in contrast to the non-ideal dispersive flow in actual reactor.     

Synthesis of ZSM‐5 by hydrothermal method with pre‐mixing in a stirred‐tank reactor

This work proposed a synthesis route of ZSM‐5 via the hydrothermal method with premixing in a stirred tank reactor (STR). Effects of various operating conditions, including pre‐mixing time, molar ratio of SiO₂/Al₂O₃, TPAOH (organic template agents) concentration, NaCl (alkali metal cations) concentration, crystallization temperature, and crystallization reaction time, on the average particle size (PS) and particle size distribution (PSD) were investigated. It was found that the pre‐mixing time in the STR significantly affect the formation of proto‐nuclei in premixing process and crystal growth in hydrothermal reaction process, and consequently influence the PS and PSD of the prepared ZSM‐5. ZSM‐5 with good thermal stability, a PS of 380 nm, PSD of 0.17–0.9 µm, pore diameter of 2.31 nm, pore volume of 0.19 cm³ · g^?1 and specific surface area of 337.25 m² · g^?1 were obtained under the optimal conditions of a crystallization reaction time of 24 h, a crystallization temperature of 130 °C, a molar ratio of SiO₂/Al₂O₃ of 200, a TPAOH concentration of 3.5 mol · L^?1, NaCl concentration of 0.3 mol · L^?1, and a pre‐mixing time of 5 h. This work indicated that the operating conditions including premixing time have a significant effect on its PS and PSD.     

Products from rapid heating of a brown coal in the temperature range 400–2300 °C

The devolatilisation behaviour of Yallourn brown coal was investigated under rapid heating conditions using two different flash pyrolysers: a fluid-bed reactor giving coal particle heating rates of 10⁴ °Cs^?1 with a gas residence time of about 0.5 s and a shock tube which generated heating rates of the order of 10⁷ °Cs^?1 and a 1 ms reaction time. Yields of products are reported covering pyrolysis temperatures in the range 400–2300 °C. Hydrocarbon gas yields reached maximum values which were remarkably similar for both reactors although occurring at different temperatures. Carbon oxide production was also similar for both reactors with CO yields reaching 30% wt/wt daf coal. These high yields of CO are very different from those reported for slow heating conditions. It appears that on flash heating, coal decomposition pathways change in a manner which increases CO yields at the expense of H₂0 and to a lesser extent C0₂, resulting in the volatilisation of additional carbon from the coal.     

Relation of the chemical structure of coal to its hydropyrolysis

The hydropyrolysis of Illinois No. 6 coal has been studied in a batch reactor, in which the reactions were initiated by explosion of $\text{H}{}_2\text{O}{}_2$ mixtures. The ratio of H₂ to O₂ was kept at 8, while the total pressure of the gas mixture was changed to vary the reaction temperature. The heating rate was ≈ 50 000 °C s^?1, and the reaction time was < 50 ms. The conversion of the feed coal increased from 19% at 620 °C to 81%at ? 1500 °C. At conversions < 50%, the gaseous product consisted of mainly CH₄ and CO in almost equal proportions, and at conversions ? 60% the concentration of CO increased. Comparison with results from a large flow reactor revealed that comparable conversions were obtained in the present batch reactor, although product distributions were markedly different from each other. The dissimilar product distribution is attributed to different reacting media: preburning of H₂ and O₂ in the flow reactor versus in situ burning of the mixture in the batch reactor. The H/C ratios of solid residues after the hydropyrolysis decreased linearly as the conversion increased, revealing that the portions of coal having high H/C ratios were preferentially gasified. This observation was substantiated by a high H/C ratio, 1.74 of the first portion of coal gasified, and by a sharp decrease in H/C ratio in subsequent gasified portions. These data indicated that aliphatic side chains (or linkages) and single-ring aromatic clusters in the feed coal were gasified first, followed by larger aromatic clusters. Semi-quantitative determination of the distribution of different aromatic clusters showed good agreement with current structural information on coal. Thus, the effects of reaction variables were explained in terms of the structural features of coal, and the ratelimiting steps in the hydropyrolysis process were identified.     

Optimization of the Dissolution of Tincal Ore in Phosphoric Acid Solutions at High Temperatures

The aim of the study was to investigate the optimization of the dissolution of tincal ore in phosphoric acid solutions at high temperatures in a batch reactor. The effect of the following parameters on the dissolution process was investigated: the reaction temperature, the phosphoric acid concentration, the particle size, and the solid-to-liquid ratio. The best conditions for the dissolution were determined using the 2⁴ factorial experimental design method. The optimum values of the parameters were experimentally determined. The effective parameters were the reaction temperature, the phosphoric acid concentration, the particle size, and the solid-to-liquid ratio. The optimum conditions resulted in the maximum boron dissolution at an acid concentration of 1 M, reaction temperature of 85°C, particle size of 4.75 mesh, and solid-to-liquid ratio of 1/6 g · mL^?1. Under these optimum conditions, the best dissolution yield was 98.26%.     

Low-Temperature Water Gas Shift Reaction on Combustion Synthesized Ce1−x Pt x O2−δ Catalyst

Catalytic activity of Pt²⁺ ion substituted CeO₂ synthesized by solution combustion method was tested for low-temperature water gas shift reaction in H₂ rich steam reformate. XPS studies show that Pt is dispersed as ions and there is no change in Pt oxidation state after the reaction. CO conversion is found to be maximum at 200 °C over Ce_1?x Pt _x O_2?δ catalysts without any methanation. The values of rate are 1.86 and 4.66 μmol/g/s at 125 and 150°C respectively with a dry gas flow rate of 6 Lh^?1 over 2% Pt/CeO₂.