纸浆黑液和钙混合催化剂进行高变质无烟煤水蒸气气化的研究

The catalytic effects of single and mixed catalysts, i.e. single 3%Ca and 5%Na-BL（black liquor） catalysts and mixed 3%Ca＋5%Na-BL catalyst, on carbon conversion, gasification reaction rate constant and activation energy, relative amount of harmful pollutant like sulphur containing gases have been investigated by thermogravimetry in steam gasification under temperature 750℃ to 950℃ at ambient pressure for three high-metarnorphous anthracites （Longyan, Fenghai and Youxia coals in Fujian Province）. The mixed catalyst of 3%Ca＋5%Na-BL increases greatly the carbon conversion and gasification rate constant by accelerating the gasification reaction C＋H2O→CO＋H2 due to presence of alkali surfacecompounds [COM], [CO2M] and exchanged calcium phenolate and calcium carboxylate （-COO）2. By adding CaCO3 into BL catalyst in gasification, in addition to improving the catalyst function and enhancing the carbon conversion, the effective desulphurization is also achieved, but the better operating temperature should be below 900℃. The homogenous and shrinking core models can be successfully employed to correlate the relations between the conversion and the gasification .time .and to estimate the reaction rate constant, The reaction acUvaUon energy and pre-exponential factor are estimated and the activation energy for mixed catalyst is in a range of 98.72-166.92 kJ·mol^-1, much less than 177.50-196.46 kJ·mol^-1 for non-catalytic steam gasification for three experimental coals.     

用于环戊烯氧化合成戊二醛反应的钨基催化剂的表征

Tungsten-containing hexagonal mesoporous silica （W-HMS） supported tungsten oxide catalysts （WOx/W-HMS） was prepared for the selective oxidation of cyclopentene with aqueous hydrogen peroxide to glutaraldehyde. X-ray diffraction （XRD） results indicated that the crystal form of the active phase （tungsten oxide） of the WOx/W-HMS catalysts was dependent on the W loading and calcination temperature. X-ray photoelectron spec- troscopy （XPS） analysis revealed that the dispersed tungsten oxides on the surface of W-HMS support consisted of a mixture of W（V） and W（VI）. It was found that a high content of amorphous W species in （5＋） oxidation state resuited in the high catalytic activity. When the W loading was up to 12% （by mass） or the catalyst precursor was treated at temperature of 623 K, the catalytic activity decreased due to the presence of WO3 crystallites and the oxidation of W（V） to W（VI） on the catalyst surface. Furthermore, NH3-temperature-programmed-desorption （NH3-TPD） analysis showed that the effects of W loading and calcination temperature on the acidity of the catalysts were related to the catalytic activity. A high selectivity of 80.2% for glutaraldehyde with a complete conversion of cyclopentene was obtained over 8%WOx/W-HMS catalyst calcined at 573 K after 14 h of reaction.     

Effects of inherent potassium on the catalytic performance of Ni/biochar for steam reforming of toluene as a tar model compound

Biochar supported nickel(Ni/BC) has been widely studied as a cheap and easy-to-prepare catalyst with potential applications in tar reforming during the gasification of low-rank fuels, such as brown coal and biomass. However, the role and behaviors of inherent K species, especially their interactions with Ni particles and the biochar support, are not well understood yet. In this work, three Ni/BC catalysts with varying K amount were prepared from raw, water-washed, and acid-washed biomass. They were used in steam reforming of toluene as a tar model compound to elucidate the effects of inherent K on the catalytic activity and stability. Detailed characterization indicated that K enhanced water adsorption due to its hydroscopicity and lowered the condensation and graphitization degrees of biochar, but the alteration to the electronic state of Ni was not observed. These effects together led to a temperature-dependent role of K. That is, at relatively low temperatures of 450 and 500 °C, toluene conversion was increased in the presence of K, due to the increased concentration of adsorbed water around Ni particles. By contrast,at relatively higher temperatures of 550 and 600 °C, although initial high activity was achieved, Ni/BC with K deactivated rapidly because of the accelerated consumption of the biochar support.     

Ni-mediated Liquid Phase Reduction of Carbonyl Compounds in the Presence of Atmospheric Hydrogen

An efficient reduction system of benzaldehyde with hydrogen under ambient pressure was developed using facile NiO catalyst. The non-aromatic solvents such as cyclohexane, tetrahydrofuran （THF） and n-hexane, and the additive with strong basicity e.g. KOH, were necessary for smooth conversion of the substrate. That the catalyst can be recovered and reused for nine times without loss of catalytic activity indicates that this catalyst is a recyclable one for benzaldehyde reduction.     

离子液体催化丁醇与盐酸反应制备丁基氯

The catalytic performance of some quaternary ammonium salts for the liquid phase reaction of butanol and hydrochloric acid at different conditions was studied experimentally and compared with the traditional catalyst （ZnCl2）. The organic ammonium catalysts investigated include ionic liquids N-butyl-N-methyl imidazolium fluoborate （[BMIM][BF4]） and N-butyl-N-methylimidazolium chloride （[BMIM]Cl） as well as hydrochloric salts of N-methylimidazol （[HMIM]Cl）, pyridine （[HPy]Cl） and triethylamine （[HEt3N]Cl）. It is shown that the intrinsic catalytic performance of all organic ammonium salts except [HEt3N]Cl is slightly superior to ZnCl2, while the selectivity of butyl chloride is nearly at the same level around 96%. The conversion of butanol increases slightly with temperature and the catalyst amount added while the variation of selectivity is not obvious. Based on the recycle experiments, the ionic liquids as catalyst for the reaction of butanol and hydrochloric acid can be used more than 5 times, which suggests great potential of using ionic liquids as novel catalyst for such reactions.     

固体超强酸催化剂SO2-4/TiO2-MoO3的制备及其催化合成缩醛（酮）

SO4^2-/TiO2-MoO3, a novel solid superacid, has been prepared and its catalytic activity at different synthetic conditions was examined with esterification of n-butanoic acid and n-butyl alcohol as probing reaction.The optimum conditions were also found, that is, the mass ratio of MoO3 used in the compound is 25%, the calcination temperature 450℃, and the soaked consistency of H2SO4 is 0.5mol.L^-1. Then it was applied in the catalytic synthesis of six similar important ketals and acetals as catalyst and revealed high catalytic activity. Under the condition that the molar ratio of aldehyde/ketone to glycol was 1:1.5, the mass ratio of the catalyst to the reactants was 0.5% and the reaction time 1.0 h, the yield of ketals and acetals reached up to 63.2%. The catalyst can be easily recovered and reused.     

离子液体催化的芳烃氯甲基化反应

Ionic liquids have been used as catalysts for Blanc reaction of toluene. The effects of reaction temperature, reaction time and dosage of the ionic liquid catalyst have been investigated, and the catalytic performance of different ionic liquid catalysts for toluene chloromethylation was also studied. The reaction was found to proceed under mild conditions with excellent conversion （up to 90%） in the absence of Lewis acids. The ionic liquids could be recycled and reused without loss of their catalytic activities.     

Catalytic ozonation of volatile organic compounds (ethyl acetate) at normal temperature

Catalytic treatments of VOCs at normal temperature can greatly reduce the cost and temperature of processing, and improve the safety factor in line with the requirements of green chemistry. Activated carbon fiber(ACF) was pretreated with 10% H_2SO_4 by single factor optimization to increase specific surface area and pore volume obviously. The catalytic ozonation performance of ACF loaded with Au, Ag, Pt and Pd noble metals on ethyl acetate was investigated and Pd/ACF was selected as the optimal catalyst which had certain stability. Pd is uniformly distributed on the surface of ACF, and Palladium mainly exists in the form of Pd~0 with a amount of Pd~(+2). The specific surface area of the catalysts gradually decreases as the loading increases. The activation energy of ethyl acetate calculated by Arrhenius equation is 113 kJ·mol~(-1). With 1% Pd loading and the concentration ratio of ozone to ethyl acetate is 3:1, catalytic ozonation performance is maximized and the conversion rate of ethyl acetate reached to 60% in 30–50 ℃ at 15,000–30,000 h~(-1).     

绝热固定床反应器甲醇脱水合成二甲醚的实验和模型研究

One-dimensional heterogeneous plug flow model was employed to model an adiabatic fixed-bed reactor for the catalytic dehydration of methanol to dimethyl ether. Longitudinal temperature and conversion profiles predicted by this model were compared to those experimentally measured in a bench scale reactor. The reactor was packed with 1.5 mm γ-Al2O3 pellets as dehydration catalyst and operated in a temperature range of 543-603 K at an atmospheric pressure. Also, the effects of weight hourly space velocity (WHSV) and temperature on methanol conversion were investigated. According to the results, the maximum conversion is obtained at 603.15 K with WHSV of 72.87 h－1.     

基于Aspen Plus的气流床煤气化炉三段平衡模型(英文)

A three stage equilibrium model is developed for coal gasification in the Texaco type coal gasifiers based on Aspen Plus to calculate the composition of product gas, carbon conversion, and gasification temperature. The model is divided into three stages including pyrolysis and combustion stage, char gas reaction stage, and gas phase reaction stage. Part of the water produced in the pyrolysis and combustion stage is assumed to be involved in the second stage to react with the unburned carbon. Carbon conversion is then estimated in the second stage by steam participation ratio expressed as a function of temperature. And the gas product compositions are calculated from gas phase reactions in the third stage. The simulation results are consistent with published experimental data.     

Laboratory-scale coal reactivity testing for entrained gasification

A relatively simple and rapid micro-gasification test has been developed for measuring gasification reactivities of carbonaceous materials under conditions which are more or less representative of an entrained gasification process, such as the Shell coal gasification process. Coal particles of < 100 μm are heated within a few seconds to a predetermined temperature level of 1000–2000 °C, which is subsequently maintained. Gasification is carried out with either CO₂ or H₂O. It is shown that gasification reactivity increases with decreasing coal rank. The CO₂ and H₂O gasification reactions of lignite, bituminous coal and fluid petroleum coke are probably controlled by diffusion at temperatures 1300–1400 °C. Below these temperatures, the CO₂ gasification reaction has an activation energy of about 100 kJ mol^?1 for lignite and 220–230 kJ mol^?1 for bituminous coals and fluid petroleum coke. The activation energies for H₂O gasification are about 100 kJ mol^?1 for lignite, 290–360 kJ mol^?1 for bituminous coals and about 200 kJ mol^?1 for fluid petroleum coke. Relative ranking of feedstocks with the micro-gasification test is in general agreement with 6 t/d plant results.     

K2CO3-catalysed steam gasification of supercritical extracted chars

The K₂C0₃-catalysed steam gasification of coal chars, obtained by the Supercritical Gas Extraction (SGE) process, is studied. Kinetics experiments used a gravimetric technique at atmospheric pressure and at temperatures ranging from 700 to 800 °C. It was found that K₂C0₃ is an effective catalyst for steam gasification of solvent extracted residue. The catalytic effect was similar to that observed for gasification of the unextracted parent coal. The gasification-time curves exhibited a sigmoid shape, which reduced to a single master curve for the various reaction temperatures studied and fitted well the predictions of the random capillary model. Activation energies, calculated using this model, varied from 155 to 173 kJ mol^?1 for the various chars studied.     

Solubility of potassium ferrate in 12 M alkaline solutions between 20°C and 60°C

The solubility of potassium ferrate (K₂FeO₄) was measured in aqueous solutions of NaOH and KOH of total concentration 12 M containing various molar ratios of KOH:NaOH in the range 12:0 to 3:9. Several analytical methods were tested for the determination of ferrate concentration. The final method chosen consisted of potentiometric titration of the ferrate sample with an alkaline solution of As₂O₃. The assumption was made that ferrate dissociates in concentrated KOH solutions predominantly to KFeO₄⁻. The solubility constant, S, defined as the product of the molar concentration of the potassium ion, K⁺, and the ferrate anion, KFeO₄⁻, was found to be 0·044 ± 0·006 mol² dm⁻⁶ for 20°C, 0·093 ± 0·004 mol² dm⁻⁶ for 40°C and 0·15 ± 0·09 mol² dm⁻⁶ for 60°C. From these results the heat of dissolution of K₂FeO₄ was calculated as −14·3 kJ mol⁻¹. At 60°C the enhanced decomposition of the ferrate at the higher temperature led to a greater deviation in solubility values compared with data for either 20°C or 40°C.     

Kinetic and thermodynamic studies on oxidative desulphurisation of organic sulphur from Indian coal at 50–150°C

This paper reports a relatively simple low-temperature non-isothermal oxidative desulphurisation of coal organic sulphur by weakening the CS bond using HgCl₂ solution to an inorganic sulphur-free high-sulphur Indian coal. When oxidised from 50°C to 150°C in air under normal atmospheric pressure, there is continuous decrease of organic sulphur content in the samples of the feed and Hg-treated coals. Desulphurisation is more in the Hg-treated coal (4.97–14.53 wt.%) than in the feed coal (3.72–10.93 wt.%). Kinetic study reveals that the oxidative desulphurisation process follows pseudo-first order kinetics and the rate constants have been found to be in the range (3.09–5.06)×10⁻⁵ s⁻¹ for feed coal and (4.19–6.80)×10⁻⁵ s⁻¹ for Hg-treated coal. The activation energies for the sulphur loss reaction in the oxidative desulphurisation process by using the pseudo-first order kinetic (feed coal: 2.21×10² J mol⁻¹; Hg-treated coal: 1.53×10² J mol⁻¹) have been found to be almost similar to those calculated by applying the Coats and Redfern's equation (feed coal: 2.19×10² J mol⁻¹; Hg-treated coal: 1.53×10² J mol⁻¹). However, the value is higher (feed coal: 3.50×10² J mol⁻¹; Hg-treated coal: 2.70×10² J mol⁻¹) when Horowitz and Metzger's equation is applied. The frequency factors computed by the pseudo-first order kinetics are very low and have been found to be 2.66×10⁻⁵ s⁻¹ for feed coal and 3.96×10⁻⁵ s⁻¹ for Hg-treated coal, suggesting very low rate of successful collisions for the formation of the activated complex. Evaluation of thermodynamic parameters viz., ΔH, ΔU, ΔS and ΔG, reveals that this oxidative desulphurisation process is non-spontaneous in nature and the degree of non-spontaneity of such a process in the feed coal is more relative to that of the Hg-treated coal.     

Catalytic hydrogenation of CO over the doped perovskite oxide YBa2Cu3O7-x catalysts

Perovskite oxide structured YBa₂Cu₃O₇-x(YBCO) has been first prepared by carbonate precipitation and then modified with palladium or ruthenium by impregnation on the perovskite oxide, while cobalt was co-precipitated simultaneously in the same pH range with perovskite oxide. After characterization the catalysts were used in the temperature range 300–450°C, in the pressure range 1–9 atmospheres and for H₂/CO ratios in the range 1–4 in a differential plug flow reactor for the hydrogenation of carbon monoxide to give hydrocarbons. The perovskite oxide (YBCO) 20% (w/w) and doped 2% (w/w) cobalt oxide catalyst were prepared by the wet chemical method from their nitrate solutions and oxidized at 950°C. Perovskite oxide (Dursun, G. & Winterbottom, J. M., J. Chem. Technol Biotechnol. 63 (1995) 113–16) was also doped with palladium and ruthenium metal by impregnation followed by oxidation at 250°C. The catalysts prepared were characterized by using TemperatureProgrammed Reduction (TPR) to observe the reduction temperature and also to measure total and metal surface area. The modified perovskite oxide on alumina, ruthenium- and cobalt-doped catalysts, has been shown to give a better conversion and also selectivity towards saturated hydrocarbons compared with palladium-doped catalyst. The temperature effect of these catalysts is more consistent, giving a steady increase of conversion with increasing temperature. Although increase of pressure increases the conversion, it causes very little change in product distribution. The activation energy of palladium- and ruthenium-doped, and cobalt co-precipitated catalysts for the reaction has been measured to be 55 kJ mol⁻¹, 75 kJ mol⁻¹ and 50 kJ mol⁻¹ respectively. A general rate equation of the form r=k[H₂]^m[CO]ⁿ has been observed and found to be applicable at the pressures and temperatures used for the catalytic system studied and found to be m≌1·0 for palladium-doped, m≌1·2 for ruthenium-doped and m≌0·95 for cobalt co-precipitated catalysts as n becomes zero or negligibly less than zero. The mechanism of reaction to produce hydrocarbons from syngas has been deduced from the results. It appeared that the carbon monoxide insertion mechanism has been more evident for palladium-doped catalysts whereas the carbide mechanism plays the main role for the ruthenium-doped and cobalt co-precipitated catalysts. © 1998 Society of Chemical Industry     

Humid aging of polyetherimide. I. Water sorption characteristics

The sorption and desorption kinetics of water into polyetherimide (ULTEM 1000) were studied at various temperatures ranging from 20 to 100°C. The water equilibrium concentration increases slightly with temperature from 1.39% (by weight) at 20°C to 1.50% at 100°C. The solubility coefficient, S, calculated from these data, and the water vapor pressure decrease with temperature. The calculated heat of dissolution H_s is close to −43 kJ mol⁻¹, which explains the low effect of temperature on the equilibrium concentration. The diffusion coefficient, D, varies from about 1.10⁻¹² m² · s⁻¹ at 20°C to about 16.10⁻¹² m² · s⁻¹ at 100°C. The apparent activation energy of diffusion, E_D, and the heat of dissolution, H_s, of water in the polymer have opposite values (respectively, +43 and −42 kJ · mol⁻¹). From this observation and a comparison of these data with water diffusion characteristics in other glassy polar polymers, it is hypothesized that the transport rate of water is kinetically controlled by the dissociation of water–polymer complexes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1439–1444, 2000     

Nonthermal plasma (NTP) activated metal–organic frameworks (MOFs) catalyst for catalytic CO2 hydrogenation

A systematic study of Ni supported on metal–organic frameworks (MOFs) catalyst (i.e., 15Ni/UiO-66) for catalytic CO₂ hydrogenation under nonthermal plasma (NTP) conditions was presented. The catalyst outperformed other catalysts based on conventional supports such as ZrO₂, representing highest CO₂ conversion and CH₄ selectivity at about 85 and 99%, respectively. We found that the turnover frequency of the NTP catalysis system (1.8 ± 0.02 s⁻¹) has a nearly two-fold improvement compared with the thermal catalysis (1.0 ± 0.06 s⁻¹). After 20 hr test, XPS and HRTEM characterizations confirmed the stability of the 15Ni/UiO-66 catalyst in the NTP-activated catalysis. The activation barrier for the NTP-activated catalysis was calculated as ~32 kJ mol⁻¹, being lower than the activation energy of the thermal catalysis (~70 kJ mol⁻¹). In situ DRIFTS characterization confirmed the formation of multiple carbonates and formates on catalyst surface activated by NTP, surpassing the control catalysts (e.g., 15Ni/α-Al₂O₃ and 15Ni/ZrO₂).     

Catalysis of gasification of coal-derived cokes and chars

Calcium is the most important in-situ catalyst for gasification of US coal chars in O₂, CO₂ and H₂O. It is a poor catalyst for gasification of chars by H₂. Potassium and sodium added to low-rank coals by ion exchange and high-rank coals by impregnation are excellent catalysts for char gasification in O₂, CO₂ and H₂O. Carbon monoxide inhibits catalysis of the CH₂O reaction by calcium, potassium and sodium; H₂ inhibits catalysis by calcium. Thus injection of synthesis gas into the gasifier will inhibit the CH₂O reaction. Iron is not an important catalyst for the gasification of chars in O₂, CO₂ and H₂O, because it is invariably in the oxidized state. Carbon monoxide disproportionates to deposit carbon from a dry synthesis gas mixture (3 vol H₂ + 1 vol CO) over potassium-, sodium- and iron-loaded lignite char and a raw bituminous coal char, high in pyrite, at 1123 K and 0.1 MPa pressure. The carbon is highly reactive, with the injection of 2.7 kPa H₂O to the synthesis gas resulting in net carbon gasification. The effect of traces of sulphur in the gas stream on catalysis of gasification or carbon-forming reactions by calcium, potassium, or sodium is not well understood at present. Traces of sulphur do, however, inhibit catalysis by iron.     

Structured Ni@NaA zeolite supported on silicon carbide foam catalysts for catalytic carbon dioxide methanation

Carbon dioxide (CO₂) conversion is an important yet challenging topic, which helps to address climate change challenge. Catalytic CO₂ methanation is one of the methods to convert CO₂, however, it is limited by kinetics. This work developed a structured Ni@NaA zeolite supported on silicon carbide (SiC) foam catalyst (i.e., Ni@NaA-SiC), which demonstrated an excellent performance with a CO₂ conversion of ~82%, being comparable to the corresponding equilibrium conversion, and CH₄ selectivity of ~95% at 400°C. The activation energy for CO₂ conversion over the 15Ni@NaA-SiC catalyst is about 31 kJ mol⁻¹, being significantly lower than that of the 15Ni@NaA pelletized catalyst (i.e., ~84 kJ mol⁻¹). Additionally, the structured catalyst was highly stable with sustained CO₂ conversion at 78.7 ± 1.4% and selectivity to CH₄ at 97.7 ± 0.2% over an 80 hr longevity test. In situ diffuse reflectance infrared Fourier transform spectroscopy-mass spectroscopy characterization revealed that catalysis over the structured catalyst proceeded primarily via the CO free mechanism.     

Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part VII. Raman spectroscopic study on the changes in char structure during the catalytic gasification in air

FT-IR/Raman spectroscopies have been used to identify the structural features of Victorian brown coal chars during the gasification in air at 400 °C. The deconvolution of the Raman spectra has allowed us to identify the main structural sites in char where preferential reaction with O₂ takes place. The presence of Na and Ca catalysts is shown to alter the reaction pathways between char and O₂. In the absence of a catalyst, the O-containing functional groups formed in char during gasification were closely associated with the aromatic structure and thus tended to loosen the aromatic structure. The non-catalysed gasification was slow and took place on some specific (especially sp³-rich or sp²–sp³ mixture) sites distributed throughout the char. In the presence of a catalyst (Na or Ca), the O-containing functional groups were not closely associated with the main aromatic structure throughout the char. The catalytic gasification reactions were localised on the sites associated with the catalysts. The preferential removal of smaller aromatic ring systems and the persistence of cross-linking structures in the presence of a catalyst mean that the large aromatic ring systems were increasingly concentrated with little flexibility, affecting the dispersion of catalyst.