添加剂对煤焦催化气化特性的影响

在自行搭建的热重分析仪上进行恒温下煤焦的催化气化实验。通过添加剂对催化剂进行预处理,可能使得催化剂有着更好的催化效果。研究了氨水和冰乙酸两种添加剂催焦样催化气化的影响,催化剂分别为CaO和Fe(NO_3)_3。分别在780、810、850、900℃进行了气化实验。研究结果表明:两种添加剂对原煤焦的气化过程影响很小;对于CaO的催化气化,氨水能起到促进气化过程的作用,冰乙酸使得催化气化反应性降低;对于Fe(NO_3)_3的催化气化,冰乙酸能促进催化气化过程,氨水则使得催化气化反应性降低。     

脱矿物质对铁镍催化煤焦—CO2气化反应性的影响

在先锋褐煤的原煤、脱矿物质煤中掺加一定量的金属Fe、Ni、Ca的硝酸盐,在固定床管式碳化炉上,600℃制焦。XRD技术测试了煤焦中金属元素的存在形态,程序升温法测定了上述煤焦的CO_2气化反应活性。结果表明,Si对Fe催化煤焦—CO_2气化反应没有影响,而Ca对Fe、Ni的催化行为有促进作用,原因在于Ca元素有助于Fe物种的还原和Ni物种在煤焦表面的分散,而Si元素以SiO_2的形式分散在煤焦中,未与Fe形成不溶体,因而不影响Fe的催化作用。     

凹凸棒石镍基催化剂对污泥气化焦油催化裂解的特性分析

以凹凸棒石为催化剂载体,采用等体积浸渍法制备了多种镍基催化剂,并对催化剂进行了XRD、SEM、BET、EDS等特性分析。在固定床反应器中对催化剂催化裂解污泥气化焦油模型化合物的特性进行了实验研究。考察了反应温度、水碳比（S/C）、气相停留时间、助剂等因素对模型化合物催化裂解特性的影响。结果表明,提高反应温度、增加S/C、延长停留时间、添加助剂均能提高催化剂的催化活性,模型化合物转化率明显增加。但是助剂含量过高反而导致催化剂催化裂解的能力减弱,模型化合物转化率下降。对比Fe、Ce、Cu、Ca 4种助剂发现,在实验范围内,增加Fe的含量,模型化合物转化率上升。当Ce、Cu、Ca助剂质量分数达到3%及以上时,转化率下降明显,甚至低于未添加助剂时的转化率。     

福建无烟煤Na2CO3催化气化过程的比表面变化特性

基于福建建欣无烟煤添加不同量Na2CO3时热天平850℃的水蒸气气化实验,考察了热解气化进程中Na2CO3的自身分解及与碳反应的失重变化。比表面分析仪测定了不同转化率煤样的吸脱等温线的演变规律,在低Na2CO3含量及低转化率时呈现为一端封闭的窄狭缝型微孔结构为主的微孔吸附Ⅰ型特征,高Na2CO3含量及高转化率时转变为有两端开口的开放性中孔和大孔吸附的Ⅱ型特征,超过12%Na2CO3饱和度时显示出裂隙孔和墨水瓶孔表面的H4型回线特征。BET及T-plot模型计算表征了不同量Na2CO3及不同转化率时的比表面积及孔径分布特性,所有比表面积均呈现随转化深度先增后减的变化,Na2CO3催化剂的加入及分散增加了碳活性点位数及气化速率,引起更多微孔的开辟、交联和微孔表面积的减小,Na2CO3添加量越大,比表面积先增后减越趋平缓。12% Na2CO3饱和度时催化剂的充分填充与均匀分散,导致更多难转化碳表面上微晶结构活性位的增加,在气化进程中会引起大量微孔开辟与交联扩孔,在深度转化终止气化反应时,所有比表面积均接近零值,表明了催化剂添加饱和度时转化程度最大及气化过程的均一性。     

K_2CO_3对兰炭催化气化特性的影响

在固定床中考察了不同K_2CO_3植入浓度和不同温度条件下兰炭催化气化特性。结果表明,5%的催化剂植入浓度主要起到填充孔隙的作用,当植入浓度增加到10%以后,催化剂发生堆积会使颗粒表面及内部形成较多孔隙。提高气化温度可提高兰炭转化率,超过750℃之后碳转化率增幅减缓,催化剂饱和装载浓度为10%。在颗粒表面和开放孔隙中的高浓度C(O)才具有较高的脱附速率,并提高CO生成速率。在非催化条件下,随着气化的进行CO/CO_2下降,而H_2/(2CO_2+CO)先增后减。在催化条件下,H_2/(2CO_2+CO)稳定在1.5～1.7。催化剂兰炭样品中出现了K_2Ca(CO_3)_2双金属碳酸盐、K_2O、KO_2等活性组分,并随催化剂植入浓度的增加而增加。催化剂植入浓度的增加会导致失活现象加重,但兰炭在750℃条件下气化1 h催化剂没有完全失活。     

高炉用冶金焦与兰炭气化反应行为研究

通过实验室模拟高炉反应条件,对高温下冶金焦炭、兰炭与CO2气化反应特性进行研究,并结合兰炭微观结构分析了其反应机理.结果表明,兰炭起始反应温度低,气化反应速率远高于冶金焦炭,并且随着温度升高而迅速增加.富碱后,碱金属可以分布到兰炭内部,使兰炭在较长时间内保持较高的反应速率.冶金焦炭结构致密,镶嵌组织含量高;兰炭结构呈层片状,比表面积大,各向同性组织含量高,易与CO2发生反应.     

煤加氢催化气化影响因素的实验研究

<正>近年来,天然气市场的强烈需求以及"富煤、贫油、少气"的能源分布特点刺激了国内学者对于煤制代用天然气的兴趣[1-2]。煤加氢气化能使产生的粗煤气中含有高浓度的甲烷,有利于生产代用天然气[3]。目前,人们在高温条件下对加氢气化反应进行了广泛的研究。为了降低气化反应温度,减少对反应设备材料的要求,同时又保持较快的气化反应     

黏结剂与阻熔剂对兰炭成型及熔融特性的影响

将大量粒径小于3mm的废弃兰炭粉末制气化型煤既可以降低气化型煤的成本,也充分利用了资源。本文采用常温加压成型工艺,重点研究了不同黏结剂对型煤性能的影响,并考察了添加阻熔剂后兰炭灰渣熔点的变化情况。结果表明,在相同添加量下,有机黏结剂制备的型煤落下强度大,但热稳定性差;而以无机黏结剂制备的型煤落下强度小,影响型煤热值,但热稳定性好。黏土1（wAl2O3>60%）既有黏结性能,又能很好地提高煤灰熔融特性。将腐殖酸钠、淀粉、黏土1复合黏结剂可以使兰炭型煤落下强度和灰熔点满足气化型煤的要求。     

钠盐对准东煤CO2吸附能力及气化特性的影响

为探究不同化学形态的钠盐对准东煤CO₂吸附能力及气化特性影响,对酸洗后的准东煤采用溶液浸渍法负载钠盐。利用热重分析仪研究了4种负载钠盐的煤样和酸洗煤样的气化反应性和CO₂吸附能力,并对5种煤样的反应动力学模型进行了分析和计算。结果表明：负载钠盐可显著降低煤样起始气化温度和气化所需活化能,提高气化反应活性指数和吸附CO₂的能力。实验选用的4种钠盐对准东煤CO₂气化反应催化作用强弱依次是：Na₂CO₃> NaHCO₃> Na₂SO₄> NaCl。煤样的CO₂强化学吸附能力可反映出煤样的CO₂气化反应活性。随机孔模型可以较好地描述酸洗煤的CO₂气化过程,而修正的随机孔模型则能更好地反映负载钠盐煤样的CO₂气化过程。     

Fe/Al_2O_3催化剂催化氧化兰炭废水

采用浸渍法制备Fe/Al_2O_3催化剂,采用BET、XRD和穆斯堡尔谱等进行结构和性能表征。以自制Fe/Al_2O_3为催化剂,应用催化湿式过氧化氢氧化技术处理COD为6 742 mg·L-1的兰炭废水,通过建立正交实验确定最佳实验条件,结果表明,在p H=4、过氧化氢添加量9.6 m L、反应时间150 min和反应温度80℃条件下,兰炭废水COD去除率达66.30%。对催化氧化后的废水进行GC-MS分析,确定最终氧化产物主要为乙酸。表明自制Fe/Al_2O_3催化剂具有优良的催化效果,并使大分子难降解有机污染物分解为易生化的小分子污染物,甚至被完全分解矿化。     

烟煤地下气化半焦对模拟废水中苯酚的脱除

以鹤壁烟煤地下气化半焦为脱除剂,对苯酚模拟废水进行脱除实验研究。采用扫描电镜、低温氮气物理脱除仪和红外光谱仪对半焦的表面特性、孔结构和表面官能团进行表征,进一步考察了半焦投加量、震荡时间、实验温度对模拟废水苯酚脱除的影响。实验结果表明:气化半焦具有微孔(小于2nm)和层状结构,微孔孔径主要分布在1~5nm之间,表面有较丰富的含氧官能团;在模拟废水苯酚浓度为100mg/L、水焦比为10:1、震荡时间为2h、脱除温度为40℃时,半焦对苯酚的脱除率和吸附容量分别为65%和0.66mg/g,气化半焦的孔结构特性和表面含氧官能团对苯酚脱除有积极作用;半焦对模拟废水中苯酚的吸附为多分子层物理吸附,其Freundlich吸附等温式为Q=0.0546C^0.6286。     

煤焦在气化合成气中高温气化反应特性

在固定床管式炉反应器中进行了煤焦在H₂O、CO₂、H₂和CO混合气氛中气化特性的实验研究,考察了反应温度、原料气组成和加煤量对产物气组成以及碳转化率的影响。实验结果表明,在各实验条件下,合成气与煤焦反应后CO流量均增加最多,H₂少量增加。煤焦与CO₂的反应受到明显抑制。混合气体通过与煤焦反应可以提高有效气（CO+H₂）的含量,实验条件下反应出口气体中有效气浓度比反应结束时最多提高3.3个百分点。反应速率受气化剂之间的竞争和气化产物的抑制作用较为明显,在1100℃和1300℃时,煤焦在相同气化剂流量的合成气中的最高反应速率分别只有在纯气化剂（水蒸气或CO₂）中最高反应速率的49%和69%。受到多种气体组分之间的相互影响,气体在孔道里的扩散和吸附对反应影响更加显著,随机孔模型可以较好地拟合此类反应,而不考虑孔结构的均相模型和缩芯模型拟合度较差。     

Potassium‐catalyzed steam gasification of ash‐free lignite coal with CO2 capture

The purpose of this research was to study steam gasification of ash‐free coal integrated with CO₂ capture in the presence of a K₂O catalyst for enhancement of the key water‐gas shift reaction and promotion of hydrogen production. To achieve this goal, gasification experiments on ash‐free coal (AFC) were carried out at varying temperatures (600, 650, 675, 700, and 750 °C) with a sorbent‐to‐carbon (CaO/C) ratio of 2 and a catalyst (K₂O) loading of 0.2 g/g (20 weight percent (wt%)) in a fixed‐bed reactor equipped with a gas chromatography analyzer. The sorbent‐to‐carbon (CaO/C) ratio of 2 is based on dry and ash‐free basis. The CaO/C ratio and K₂O wt% were chosen to maximize hydrogen production based on our previously determined optimal values. The AFC was originally extracted from raw lignite coal using organic solvents, which allowed the sorption‐enhanced gasification to be conducted with minimal ash‐catalyst interactions. The effect of temperature on the yield and the initial reaction rate were investigated. The optimal reaction temperature of 675 °C was determined. Carbon balance and final carbon conversions were calculated based on the residue analysis. Activation energy was also calculated using intrinsic kinetics of the reaction. In this study, using AFC offered the potential advantage of operating the gasification process with catalyst recycle.     

改性活性半焦脱除烟气中SO2的反应动力学

在固定床反应器中，研究用改性活性半焦来脱除烟气中SO₂的动力学问题。考察半焦粒径、反应温度和空速对SO₂转化率的影响，建立了本征动力学方程。反应级数为一级，表观活化能为10.058 kJ·mol^-1，指前因子为69.622 2。     

Application of K2CO3 catalysts in the coal gasification process using nuclear heat

Conventional gasification processes use coal not only as feedstock to be gasified but also for supply of energy for reaction heat, steam production, and other purposes. With a nuclear high temperature reactor (HTR) as a source for process heat, it is possible to transform the whole of the coal feed into gas. This concept offers advantages over existing gasification processes: saving of coal, as more gas can be produced from coal; less emission of pollutants, as the HTR is used for the production of steam and electricity instead of a coal-fired boiler; and a lower production cost for the gas. However, the process has the disadvantage that the temperature is limited to the outlet temperature (950 °C max) of the helium cooling gas of the HTR. Therefore the possibility of catalytic steam gasification was examined. Model calculations based on experimental results show that use of 3–4 wt% relative to coal of K²CO³ catalyst increases the throughput of a large scale nuclear gasification plant by ≈65%, while gas production costs decrease by ≈15%. Corrosion by catalysts is not significant at low concentration (< 5 wt%) and low temperature (< 900 °C).     

Catalytic activity of physically-mixed nickel compounds on the CO2 gasification of phenol-formaldehyde resin char

In order to account for the various activities of different nickel compounds in low temperature catalytic gasification of carbon the reducibility of individual nickel compounds in carbon dioxide to metallic was studied by thermogravimetry and the behaviour of mixture of nickel salts with a phenol-nickel formaldehyde resin char was investigated by temperature-programmed X-ray diffraction analysis. A correlation was found between the order of reducibility of the nickel salts and their order of activity in catalytic gasification. Low temperature gasification up to 98 wt% was demonstrated for char mixed with nickel acetate (up to 9/10 wt% Ni), which suggests that there may be good prospects for finding a method of complete gasification with nickel.     

CO2 gasification kinetics of two alberta coal chars

CO₂ gasification kinetics of chars from two Alberta coals (Obed Mountain, high volatile bituminous and Highvale, subbituminous) have been studied using a thermogravimetric analyzer (TGA) and a fixed bed reactor. Charification and gasification reactions were performed sequentially in both the TGA instrument and in the fixed bed reactor to simulate real gasifier operating conditions. TGA and fixed bed data were processed numerically to evaluate the kinetic rate of CO₂ gasification of the chars. Calculated gasification kinetics could be correlated using both the volume reaction and the grain models. Activation energies of the kinetic rate constants were near 200 kJ/mol for both Highvale and Obed Mountain coal chars using the TGA data. The activation energies calculated for the Obed Mountain coal char using the fixed bed reactor were about 250 kJ/mol. For all the cases studied the calculated activation energies were nearly the same for both the volume and grain reaction models.     

Hydrogen production by catalytic gasification of cellulose in supercritical water

Cellulose, one of the important components of biomass, was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure. K₂CO₃ and Ca(OH)₂ were selected as the catalysts (or promoters). The temperature was kept between 450°C and 500°C while pressure was maintained at 24–26 MPa. The reaction time was 20 min. Experimental results showed that the two catalysts had good catalytic effect and optimum amounts were observed for each catalyst. When 0.2 g K₂CO₃ was added, the hydrogen yield could reach 9.456 mol·kg⁻¹ which was two times of the H₂ amount produced without catalyst. When 1.6 g Ca(OH)₂ was added, the H₂ yield was 8.265 mol·kg⁻¹ which is lower than that obtained using K₂CO₃ as catalyst but is still 1.7 times that achieved without catalyst. Comparing with the results obtained using K₂CO₃ or Ca(OH)₂ alone, the use of a combination of K₂CO₃ and Ca(OH)₂ could increase the H₂ yield by up to 2.5 times that without catalyst and 25% and 45% more than that obtained using K₂CO₃ and Ca(OH)₂ alone, respectively. It was found that methane was the dominant product at relatively low temperature. When the temperature was increased, the methane reacts with water and is converted to hydrogen and carbon dioxide. __________ Translated from Journal of Chemical Engineering of Chinese Universities, 2007, 21(3): 436–441 [译自: 高校化学工程学报]     

现代煤气化技术及其煤种的适应性分析

结合国内外煤气化技术发展现状与趋势,讨论了煤质特性对气化过程的影响及其在不同气化炉型中的适应性。分析表明,煤种的多样性及气化工艺的选择促进了煤气化技术的快速发展,气流床和流化床代替固定床是煤气化技术发展的必然所趋。在充分认识各类煤气化技术优缺点的基础上,应发挥优势,针对煤种选用炉型,开发具有单炉生产能力高、煤种适应性强、气体成分可调等优势的加压气化技术以及可有效利用煤气高温显热的两段或多段式气化技术。