福建无烟煤Na_2CO_3催化气化过程的比表面变化特性  

Variation of specific surface area in catalytic gasification process of Fujian anthracite with Na_2CO_3 catalyst

作　　者：陈彦[1,2] 张济宇[1] 

机构地区：[1]福州大学化学工程技术研究所,福建福州350002 [2]福建农林大学材料工程学院,福建福州350003

出　　处：《化工学报》2012年第8期2443-2452,共10页CIESC Journal

基　　金：国家自然科学基金项目(20376014);福建省科技厅重点资助项目(HG99-01)~~

摘　　要：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。Based on the steam gasification experiments of ＂Fujian Jianxin＂ anthracite with different catalyst loadings of Na2CO3 in the thermal balance at 850℃,decomposition of Na2CO3 itself and mass loss arising from the reaction of Na2CO3 with carbon in coal were examined.Also,the change of adsorption-desorption isotherms of coal samples at different conversions were measured with the specific surface area analyzer.Type Ⅰ adsorption-desorption of a narrow slit micropore configuration with a close end was mainly shown at a lower Na2CO3 loading and lower conversions,while type Ⅱ adsorption-desorption of open mesopores and macropores with two-end opening holes was formed at a higher Na2CO3 loading and higher conversions.H4-type hysteresis loop with slit and ink-bottle pore surface appeared at and beyond the catalyst saturation loading of 12% Na2CO3.The specific surface area and pore-size distribution at different Na2CO3 loadings and conversions were calculated using BET equation and T-plot model.These calculation indicated that all of specific surface area appeared to be increasing at first then decreasing with increasing conversion extent of coal.The split and crosslinking of more micropores and the reduction of micropore specific surface area were the result of the increase of active sites of carbon and gasification rate due to the loading and dispersing of Na2CO3 catalyst.The change of specific surface area with increasing at first then decreasing became more smooth with more loading of Na2CO3.At the catalyst saturation loading of 12% Na2CO3,the sufficient filling and uniform dispersion of catalyst led to increase of active sites on micro-crystalline structure surface of more inert carbon and the split and crosslinking expansion of more micropores in the gasification process.However,at the termination gasification reaction with deep conversion,all of specific surface area were close to zero,clearly showing maximum conversion of coal and uniform gasification at catalyst saturation loading.

关 键 词：水蒸气催化气化 转化率 吸脱等温线 煤比表面积 催化剂装载饱和度 

分 类 号：TQ54[化学工程—煤化学工程]