TY - THES

T1 - Influence of process parameters variation and sulfur-poisoning on a commercial steam-reforming catalyst

AU - Pollesböck, Fabian

N1 - embargoed until 28-10-2016

PY - 2014

Y1 - 2014

N2 - The goal of this work was to investigate a commercial catalyst based on noble metals, in terms of its performance for steam reforming of product gas from a dual fluidized bed biomass gasification plant. The experiments were carried out on a laboratory scale unit, consisting of a glass tube with an inner diameter of 8 mm and a height of 1000 mm, where the cylindrical hollow catalyst pellets were placed inside. The feed gasflow was around 40 L/h under atmospheric pressure. The process parameters were varied within their possible ranges. The reactor temperature was set between 700 °C and 900 °C, the spacevelocity (SV) ranged from 6000 1/h to 11000 1/h and the steam-to-carbon ratio (S/C) was varied between 1 and 3. Four different feedstock gases with varying amounts of dihydrogen sulfide (H2S) were used for the experiments. The thermodynamic equilibrium concentrations couldn't be reached during the experiments with the tested catalyst. The highest conversion rates for methane were about 60 %, which corresponded to a methane concentration of 3 % in the output stream. The trends suggested that higher temperatures than 900 °C would lead to even higher conversion rates, but the temperature was restricted due to material limitations. The steam-to-carbon ratio influenced primarily the hydrogen yield, which increased with more steam in the inlet. A maximum methane conversion was reached at an S/C-ratio of around 2. The spacevelocity had little influence on the resulting gas composition, however the conversion rates increased slightly at lower spacevelocities. On the contrary, the influence of H2S in the input gas had significant influence on the reforming reactions. Even at low concentrations of 50 ppm H2S and an exposure time of 20 min, the conversion rates dropped. Higher sulfur concentrations (> 100 ppm) caused the conversion rate of methane to fall even below 10 %. The results of this study are intended to be used for advanced simulation models for steam reforming including sulfur-components. Since gas mixtures from biological feedstocks usually contain a large amount of sulfur components, fundamental research for an efficient treatment of these gases for applications in chemical industry or mobility is required.

AB - The goal of this work was to investigate a commercial catalyst based on noble metals, in terms of its performance for steam reforming of product gas from a dual fluidized bed biomass gasification plant. The experiments were carried out on a laboratory scale unit, consisting of a glass tube with an inner diameter of 8 mm and a height of 1000 mm, where the cylindrical hollow catalyst pellets were placed inside. The feed gasflow was around 40 L/h under atmospheric pressure. The process parameters were varied within their possible ranges. The reactor temperature was set between 700 °C and 900 °C, the spacevelocity (SV) ranged from 6000 1/h to 11000 1/h and the steam-to-carbon ratio (S/C) was varied between 1 and 3. Four different feedstock gases with varying amounts of dihydrogen sulfide (H2S) were used for the experiments. The thermodynamic equilibrium concentrations couldn't be reached during the experiments with the tested catalyst. The highest conversion rates for methane were about 60 %, which corresponded to a methane concentration of 3 % in the output stream. The trends suggested that higher temperatures than 900 °C would lead to even higher conversion rates, but the temperature was restricted due to material limitations. The steam-to-carbon ratio influenced primarily the hydrogen yield, which increased with more steam in the inlet. A maximum methane conversion was reached at an S/C-ratio of around 2. The spacevelocity had little influence on the resulting gas composition, however the conversion rates increased slightly at lower spacevelocities. On the contrary, the influence of H2S in the input gas had significant influence on the reforming reactions. Even at low concentrations of 50 ppm H2S and an exposure time of 20 min, the conversion rates dropped. Higher sulfur concentrations (> 100 ppm) caused the conversion rate of methane to fall even below 10 %. The results of this study are intended to be used for advanced simulation models for steam reforming including sulfur-components. Since gas mixtures from biological feedstocks usually contain a large amount of sulfur components, fundamental research for an efficient treatment of these gases for applications in chemical industry or mobility is required.

KW - steam reforming

KW - catalysis

KW - catalyst

KW - poisoning

KW - h2s

KW - dihydrogen sulfide

KW - methane

KW - ch4

KW - dampfreformierung

KW - reformierung

KW - ch4

KW - methan

KW - schwefelwasserstoff

KW - h2s

KW - katalyse

KW - katalysator

M3 - Master's Thesis

ER -