Thermal Genesis Simulation and Adsorption Mechanism of H2S in Coal

Author:Wu Jia Hao

Supervisor:yu jing zuo fu xue hai


Degree Year:2019





The simulation experiments of coal pyrolysis and thermochemical sulfate reduction(TSR)reaction under different conditions were conducted by using the low-rank coal samples.The concentration/yield of H2S and other gas were analyzed concerning two different thermal simulation modes,as well as the thermal genesis mechanism of H2S.Additionally,both the physical and molecular simulation were conducted to highlight the adsorption of H2S by using coal samples of various ranks.The influence factors of H2S adsorption were clarified to reveal the adsorption essences.The results indicated that:(1)TSR reaction is the main source of thermogenic H2S.Heavy hydrocarbons are more likely to participate in TSR reaction than CH4.There exists synergistic effect for the release of H2S and CO2.(2)The release characteristics of H2S in TSR reaction manifests as segmentation features with the increasing temperature,which includes the initiation stage of TSR,co-generation stage of TSR reaction and sulfur compounds decomposition,and the autocatalytic stage of TSR.(3)TSR reaction is controlled by catalytic capacity of sulfate,salinity and coal particle size.The greater electron inductive effect reduces the energy barrier of TSR reaction,the greater salinity promotes the formation of contact ion pairs and the smaller coal particle size enhances the mass transfer and heat transfer of TSR reaction,which are all beneficial to the reaction.(4)The adsorption of H2S in coal was a physical,spontaneous,and exothermic process.For H2S absorbing onto coal of different ranks,the Langmuir and T-BET model were suitable for characterizing the adsorption properties of low,and high-ranks respectively.Coal has a higher adsorption affinity for H2S than for CH4.(5)The H2S adsorption affinity is positively related to coal ranks,vitrinite content,and fixed carbon yield,however,it is negatively related to inertinite,moisture,ash,and volatile matter.High temperature and greater coal particle size are not favorable for H2S adsorption.(6)The adsorption of H2S onto coal mainly rely on van der Waals force and electrostatic force.The interaction between H2S and hydroxyl groups is the greatest,and the interaction with other oxygen-containing functional groups and methyl groups is weaker than nitrogen-containing functional groups.These above results can provide significant guidance to enrich and perfect the mechanisms on H2S generation and adsorption in coal.There are 52 figures,29 tables and 342 references in this dissertation.