【作者】 王涛；

【导师】 张立强；

【作者基本信息】 山东大学 ， 能源动力（专业学位）， 2023， 硕士

【摘要】 我国是钢铁生产和使用大国,钢铁生产过程副产的高炉煤气是可燃气体,但由于含有污染气体H2S,严重影响了高炉煤气的输送和使用,在高炉煤气输送过程中会造成管道腐蚀;高炉煤气燃烧后会产生SO2污染气体。因此,开发高效的H2S脱除技术具有重要意义。目前,高炉煤气中H2S脱除技术主要采用湿法脱硫和干法脱硫。吸附法脱硫技术因投资省、运行费用低逐渐受到关注,其中分子筛吸附法硫化氢脱硫技术已经得到工业应用。活性炭作为一种良好的吸附剂,具有丰富的孔隙结构和官能团,与分子筛相比,价格便宜,工艺简单,可重复利用,且可以实现硫资源的回收利用,活性炭的H2S吸附性能是制约其工艺经济性的重要因素。活性炭对H2S的吸附主要受其物理化学性质和吸附条件的影响,因此本文首先研究活性炭种类对H2S吸附的影响,以明确活性炭物理性质与H2S吸附关系;并研究不同吸附条件下H2S的吸附特性,获得高吸附容量的操作条件。针对吸附容量低的问题,提出了氮掺杂的活性炭改性方法,并研究了掺氮活性炭吸附H2S的吸附产物与循环吸附性能。本文选用六种不同活性炭在干燥无氧条件下对H2S进行吸附,研究发现活性炭孔隙以微孔为主时,活性炭的比表面积越大,吸附H2S的性能越好,更大的比表面积可以为吸附H2S提供更多的活性位点,有助于H2S的吸附;当活性炭比表面积相似时候,活性炭微孔和中大孔结构相近,呈现分级孔结构时,吸附性能最好。活性炭微孔吸附硫化氢后,会向中大孔转移,从而促进吸附。对比不同吸附条件对活性炭吸附性能的影响,发现在30～90℃之间,随着温度升高,活性炭对H2S吸附效率提高;低浓度氧气可以促进活性炭吸附H2S,活性炭吸附氧气可以产生氧自由基,促进H2S的化学吸附,高浓度氧气会抑制活性炭吸附H2S,氧气会占据活性位点,抑制催化作用;水蒸气的加入可以提高活性炭吸附硫化氢的性能,随着水蒸气浓度增大,吸附性能逐渐增强,水蒸气在活性炭表面形成水膜,促进硫化氢解离和氧自由基形成,从而促进活性炭催化氧化性能。针对原始活性炭吸附硫容低的问题,本文采用水热法与NH3退火协同改性法对竹溪1200活性炭进行氮掺杂改性,通过改变水热温度、100 ml水中含氮有机物质量、退火温度等变量,探究了协同掺氮方法对活性炭物理化学性质的影响机制,制备出物理性质参数接近,含氮量梯级变化,含氮官能团种类可调的改性活性炭。研究发现掺氮活性炭在比表面积和孔隙结构与原始活性炭相近情况下,其吸附和催化氧化性能高于原始活性炭,氮掺杂可以提高活性炭催化氧化性能;掺氮活性炭比表面积和微孔占比接近的情况下,随着样品中N-6官能团绝对含量的增加,样品的吸附硫容也逐渐增加;活性炭样品中物理性质和含氮量处于同一水平下,N-6官能团占比越高,吸附和催化氧化硫化氢的性能越好。吸附后活性炭比表面积减少,从1369.50m2/g减少到998.08m2/g,且微孔孔容减少明显。样品的XPS分析表明掺氮活性炭催化氧化H2S的产物主要有S单质,亚硫酸盐和硫酸盐,其中S单质为主要产物。吸附后N-6官能团峰面积比吸附前有一定程度的减少,相反N-5官能团的峰面积在增加;因此活性炭中含氮官能团对H2S起到催化氧化作用的是N-6官能团。对吸附H2S后的活性炭进行循环再生实验发现,SO2的释放温度范围较集中,在220～500℃之间,220℃开始出现SO2,300℃达到峰值;H2S释放的温度范围集中在360～500℃之间,360℃开始出现H2S,470℃达到峰值;对第一次热再生产物进行硫平衡分析,催化产物中有75%左右的H2S转化为S单质。随着循环次数的增加,活性炭吸附硫容下降明显,由第一次的101.21mg/g减少到第五次的30.61mg/g;活性炭的比表面积、微孔孔容和总孔容总体呈下降趋势,但差异较小,因此推测物理性质不是吸附硫容下降的主要影响因素。多次循环再生后活性炭的元素分析表明,活性炭中S元素增加,N元素减少,因此含氮官能团的分解以及含硫物质解析不完全是吸附硫容下降的主要影响因素。更多还原

【Abstract】 China is a large country of steel production and use,steel production process by-product of blast furnace gas is a combustible gas.Because of the contaminated gas H2S,it seriously affects the transmission and use of blast furnace gas,and causes pipeline corrosion in the process of blast furnace gas transmission;the combustion of blast furnace gas produces SO2 pollution gas.Therefore,it is important to develop efficient H2S removal technology.At present,H2S removal technology in blast furnace gas mainly uses wet desulfurization and dry desulfurization.Adsorption desulfurization technology is gradually gaining attention because of the saving investment and low operating cost,among which the molecular sieve adsorption method of hydrogen sulfide desulfurization technology has been industrially applied.Activated carbon as a good adsorbent with rich pore structure and functional groups,compared with molecular sieve,is cheap,simple process,reusable,and can achieve the recycling of sulfur resources,the H2S adsorption performance of activated carbon is an important factor governing its process economics.The adsorption of H2S by activated carbon is mainly influenced by its physicochemical properties and adsorption conditions,so this paper first investigates the effect of activated carbon type on H2S adsorption to clarify the association between physical properties of activated carbon and H2S adsorption and to study the adsorption characteristics of H2S under different adsorption conditions and to obtain the operating conditions for high adsorption capacity.For the problem of low adsorption capacity,a nitrogen-doped activated carbon modification method is proposed,and the adsorption products and cyclic adsorption performance of nitrogen-doped activated carbon for H2S adsorption are investigated.In this paper,six different activated carbons were selected for the adsorption of H2S under dry and oxygen-free conditions.It is found that when the pores of activated carbon are mainly microporous,the specific surface area of activated carbon is more lager,the performance of H2S adsorption is more better.The larger specific surface area can provide more active sites for H2S adsorption,which helps H2S adsorption.When the specific surface area of activated carbon is similar,the adsorption performance is best when the microporous and mesoporous structures of activated carbon are similar and present a graded pore structure.After adsorption of hydrogen sulfide by activated carbon micropores,it will transfer to medium and large pores,thus promoting adsorption.Comparing the effects of different adsorption conditions on the adsorption performance of activated carbon,it was found that the adsorption efficiency of activated carbon for H2S increases with increasing temperature between 30 and 90℃.Low concentration of oxygen can promote the adsorption of H2S by activated carbon,which can generate oxygen radicals to promote the chemisorption of H2S,and high concentration of oxygen can inhibit the adsorption of H2S by activated carbon,which can occupy the active site and inhibit the catalytic effect.The addition of water vapor can improve the performance of activated carbon in adsorption of hydrogen sulfide.As the concentration of water vapor increases,the adsorption performance is gradually enhanced,and water vapor forms a water film on the surface of activated carbon,which promotes hydrogen sulfide dissociation and oxygen radical formation,thus promoting the catalytic oxidation performance of activated carbon.To address the problem of low sulfur adsorption capacity of the original activated carbon,this paper adopts a hydrothermal method and NH3 annealing synergistic modification method for the nitrogen doping modification of Zhuxi 1200 activated carbon.By changing variables such as hydrothermal temperature,mass of nitrogen-containing organic matter in 100 ml of water and annealing temperature,the mechanism of the effect of synergistic nitrogen doping method on physicochemical properties of activated carbon was investigated,and modified activated carbon with close physical property parameters,graded variation of nitrogen content and adjustable types of nitrogen-containing functional groups was prepared.It was found that the adsorption and catalytic oxidation performance of nitrogen-doped activated carbon was higher than that of the original activated carbon when the specific surface area and pore structure were similar to those of the original activated carbon,and nitrogen doping could improve the catalytic oxidation performance of the activated carbon.The adsorption sulfur capacity of the samples increased gradually with the increase of the absolute content of N-6 functional groups in the samples when the specific surface area and the percentage of micropores of the nitrogen-doped activated carbon were close.The percentage of N-6 functional groups in the activated carbon samples with the same level of physical properties and nitrogen content is more higher,the performance of adsorption and catalytic oxidation of hydrogen sulfide is more better.The specific surface area of activated carbon decreased after adsorption from 1369.50 m2/g to 998.08 m2/g,and the microporous pore volume decreased significantly.The XPS analysis of the samples showed that the products of H2S oxidation catalyzed by nitrogen-doped activated carbon were mainly S monomer,sulfite and sulfate,with S monomer as the main product.After adsorption,the peak area of N-6 functional group decreased to a certain extent compared with that before adsorption,while the peak area of N-5 functional group increased;therefore,the catalytic oxidation of H2S by nitrogen-containing functional groups in activated carbon was carried out by N-6 functional group.The cycle regeneration experiment of activated carbon after H2S adsorption found that the release temperature range of SO2 was concentrated between 220～500℃,with SO2 starting to appear at 220℃ and peaking at 300℃;the release range of H2S was concentrated between 360～500℃,with H2S starting to appear at 360℃ and peaking at 470℃.The sulfur equilibrium analysis of the first thermal reproduction product showed that about 75%of the catalytic product was converted from H2S to S monomer.As the number of cycles increased,the activated carbon adsorption sulfur capacity decreased significantly,from 101.21 mg/g in the first to 30.61 mg/g in the fifth.The specific surface area,microporous pore capacity and total pore capacity of activated carbon showed an overall decreasing trend,but the differences were small,so it was speculated that the physical properties were not the main influencing factors for the decreasing adsorption sulfur capacity.The elemental analysis of the activated carbon after multiple cycles of regeneration showed that the S element increased and the N element decreased in the activated carbon,so the decomposition of the nitrogen-containing functional groups and the incomplete resolution of sulfur-containing substances were the main influencing factors for the decrease of the adsorption sulfur capacity.更多还原