The slags from iron-steel and zinc industries are rich in metal oxide contents like FeO, MnO, CaO. However, these slags are not used extensively, except some usage in the cement industry. These slags can be used in removing H2S from waste gases from different industrial sources. The purpose of this research is to study the effect of initial concentration of H2S on the capacity and sorbent efficiency of waste materials from iron-steel and zinc industries. Experiments were conducted in a 25 mm-quartz reactor with simulated gases containing H2S as reactive gas. Breakthrough curves for sulfidation reactions were obtained for 3000 ppmv, 4000 ppmv and 5000 ppmv initial H2S concentrations at the reaction temperature range of 500&deg / C&ndash / 700&deg / C. According to the results obtained from the experiments, the H2S removal capacity of both slags increased with increasing reaction temperature, however, the H2S removal capacity of the slags decreases as the initial H2S concentration increases. Cyclic sulfidation and regeneration tests were applied to both steel and zinc slags in order to determine the regenerability of the slags. In cyclic tests, zinc slag gave better results than steel slag. A &ldquo / Deactivation Model&rdquo / was used in order to fit the breakthrough curves obtained experimentally to the breakthrough curves predicted from the deactivation model. A very good fit was obtained for both steel and zinc slags. Zinc slag was shown to be more suitable for gas cleanup than steel slag taking into account its high H2S removal efficiency, regenerability and low cost (almost free of charge).

Made available in DSpace on 2014-12-17T15:01:54Z (GMT). No. of bitstreams: 1 LeopoldoOAR_TESE.pdf: 2477409 bytes, checksum: 8a0937fc273e62c20239012357028d11 (MD5) Previous issue date: 2012-03-02 / Amorphous silica-alumina and modified by incipient impregnation of iron, nickel, zinc and chromium were synthetized in oxide and metal state and evaluated as catalysts for the chloromethane conversion reaction. With known techniques their textural properties were determined and dynamics techniques in programmed temperature were used to find the acid properties of the materials. A thermodynamic model was used to determine the adsorption and desorption capacity of chloromethane. Two types of reactions were studied. Firstly the chloromethane was catalytically converted to hydrocarbons (T = 300 450 oC e m = 300 mg) in a fixed bed reactor with controlled pressure and flow. Secondly the deactivation of the unmodified support was studied (at 300 ?C and m=250 g) in a micro-adsorver provided of gravimetric monitoring. The metal content (2,5%) and the chloromethane percent of the reagent mixture (10% chloromethane in nitrogen) were fixed for all the tests. From the results the chloromethane conversion and selectivity of the gaseous products (H2, CH4, C3 and C4) were determined as well as the energy of desorption (75,2 KJ/mol for Ni/Al2O3-SiO2 to 684 KJ/mol for the Zn/Al2O3-SiO2 catalyst) considering the desorption rate as a temperature function. The presence of a metal on the support showed to have an important significance in the chloromethane condensation. The oxide class catalyst presented a better performance toward the production of hydrocarbons. Especial mention to the ZnO/Al2O3-SiO2 that, in a gas phase basis, produced C3 83 % max. and C4 63% max., respectively, in the temperature of 450 oC and 20 hours on stream. Hydrogen was produced exclusively in the FeO/Al2O3-SiO2 catalysts (15 % max., T = 550 oC and 5,6 h on stream) and Ni/SiO2-Al2O3 (75 % max., T = 400 oC and 21,6 h on stream). All the catalysts produced methane (10 ? 92 %), except for Ni/Al2O3-SiO2 and CrO/Al2O3-SiO2. In the deactivation study two models were proposed: The parallel model, where the product production competes with coke formation; and the sequential model, where the coke formation competes with the product desorption dessorption step. With the mass balance equations and the mechanism proposed six parameters were determined. Two kinetic parameters: the hydrocarbon formation constant, 8,46 10-4 min-1, the coke formation, 1,46 10-1 min-1; three thermodynamic constants (the global, 0,003, the chloromethane adsorption 0,417 bar-1, the hydrocarbon adsorption 2,266 bar-1), and the activity exponent of the coke formation (1,516). The model was reasonable well fitted and presented a satisfactory behavior in relation with the proposed mechanism / S?lica alumina amorfa e modificada por impregna??o incipiente de precursores de ferro, n?quel, zinco e cromo foram sintetizados na forma de ?xido e reduzidos, tendo sido posteriormente avaliados como catalisadores na convers?o de clorometano em hidrocarbonetos. Propriedades texturais e t?cnicas din?micas em temperatura programada foram usadas para a determina??o das propriedades ?cidas dos materiais. Um modelo termodin?mico para representar a capacidade de adsor??o e dessor??o de clorometano foi avaliado. Dois tipos de rea??es foram abordados. No primeiro, o clorometano foi convertido cataliticamente a hidrocarbonetos (T = 300 450 oC e m = 300 mg) em um reator de leito fixo catal?tico com controle de fluxo, press?o e vaz?o m?ssica e, no segundo, com o suporte puro (T = 300 oC e m = 250 mg) foi estudado a rea??o de desativa??o do catalisador pelo coque em um micro adsorvedor com monitoramento gravim?trico. O teor de metal no suporte (2,5 %) e o percentual de clorometano na mistura (10 %) foram mantidos constantes durante os experimentos. Com os resultados obtidos foram avaliadas a convers?o e a seletividade dos produtos gasosos, ou seja, H2, CH4, C3 e C4 bem como a energia da etapa de dessor??o (75,2 KJ/mol para o Ni/Al2O3-SiO2 e 684 KJ/mol para o catalisador Zn/Al2O3-SiO2), considerando a taxa de adsor??o do g?s em fun??o da temperatura. A presen?a do metal no suporte mostrou uma import?ncia significativa em termos de atividade na rea??o de condensa??o do clorometano. Os catalisadores na forma de ?xido apresentaram melhor desempenho para obten??o de hidrocarbonetos. ? poss?vel destacar o ZnO/Al2O3-SiO2 que , em termos de constituinte gasoso, produziu apenas C3 (M?x. de 83 %) e C4 (M?x. de 63%), respectivamente, na temperatura de 450 oC e 20 horas de rea??o,. O g?s hidrog?nio foi formado exclusivamente com os catalisadores FeO/Al2O3-SiO2 (M?x. de 15 %, T = 550 oC e tempo de rea??o de 5,6 h) e Ni/SiO2-Al2O3 (M?x. 75 %, T = 400 oC e tempo de rea??o de 21,6 h). Todos os catalisadores produziram o g?s metano (10 ? 92 %), salvo os do tipo Ni/Al2O3- SiO2 e CrO/Al2O3-SiO2. No estudo com o suporte puro foram propostos dois modelos de iii desativa??o, do tipo paralelo, onde a forma??o do produto compete com a forma??o de coque e o sequencial, onde a etapa de dessor??o ? a competidora. Com as equa??es do balan?o de massa baseadas no mecanismo proposto foram determinados duas constantes cin?ticas (a primeira de valor 8,01?10-4 min-1, relacionada ? etapa da forma??o de hidrocarbonetos e a segunda, 1,46?10-1 min-1, ao coque depositado no s?tio do material), tr?s constantes de equil?brio (a global 0,003, relativa ao clorometano 0,417 bar-1, e a de forma??o de hidrocarbonetos 2,266 bar-1) e o do perfil do fator de atividade (1,516). Em termos de ajustes, o modelo representou um comportamento satisfat?rio em rela??o ao mecanismo proposto