Gas phase potassium effects and the role of the support on the tar reforming of biomass-derived producer gas over sulfur-equilibrated Ni/MgAl2O4

Biomass gasification is a sustainable way to convert biomass residues into valuable fuels and chemicals via syngas production. However, several gas impurities need to be removed before the final sy..

CO2 gasification reactivity of char from high-ash biomass

Biomass char produced from pyrolysis processes is of great interest to be utilized as renewable solid fuels or materials. Forest byproducts and agricultural wastes are low-cost and sustainable biomass feedstocks. These biomasses generally contain high amounts of ash-forming elements, generally leading to high char reactivity. This study elaborates in detail how chemical and physical properties affect CO2 gasification rates of high-ash biomass char, and it also targets the interactions between these properties. Char produced from pine bark, forest residue, and corncobs (particle size 4–30 mm) were included, and all contained different relative compositions of ash-forming elements. Acid leaching was applied to further investigate the influence of inorganic elements in these biomasses. The char properties relevant to the gasification rate were analyzed, that is, elemental composition, specific surface area, and carbon structure. Gasification rates were measured at an isothermal condition of 800 °C with 20% (vol.) of CO2 in N2. The results showed that the inorganic content, particularly K, had a stronger effect on gasification reactivity than specific surface area and aromatic cluster size of the char. At the gasification condition utilized in this study, K could volatilize and mobilize through the char surface, resulting in high gasification reactivity. Meanwhile, the mobilization of Ca did not occur at the low temperature applied, thus resulting in its low catalytic effect. This implies that the dispersion of these inorganic elements through char particles is an important reason behind their catalytic activity. Upon leaching by diluted acetic acid, the K content of these biomasses substantially decreased, while most of the Ca remained in the biomasses. With a low K content in leached biomass char, char reactivity was determined by the active carbon surface area.publishedVersio

Synteza węglowodorów podczas pirolizy metanu

The catalyzed conversion of acetylene to higher hydrocarbons has been studied by many researchers. The importance of these processes is determined by the fact that a successful conversion of this type will create technologies for obtaining cheap alternative synthetic fuel. Acetylene can be obtained in large quantities from coal and methane, which opens up the possibility of obtaining the specified synthetic fuel. However, the lack of an effective catalyst for continuous conversion has not allowed the development of this alternative fuel route. Features of hydrocarbon synthesis during methane pyrolysis, based on modified catalysts, are presented in the paper. It is demonstrated that production of hydrocarbons from pyrolysis gas using modified catalysts can be intensified.Katalityczna konwersja acetylenu do wyższych węglowodorów była przedmiotem badań wielu badaczy. Znaczenie tych procesów determinuje fakt, że udana konwersja tego typu pozwoli nam opracować nowe technologie pozyskiwania taniego alternatywnego paliwa syntetycznego. Acetylen można uzyskać w dużych ilościach z węgla i metanu, co otwiera możliwość uzyskania określonego paliwa syntetycznego. Jednak brak skutecznego katalizatora do ciągłej konwersji nie pozwolił na opracowanie tej alternatywnej drogi paliwowej. W artykule przedstawiono cechy syntezy węglowodorów podczas pirolizy metanu na modyfikowanych katalizatorach. Wykazano, że można zwiększyć produkcję węglowodorów z gazu pirolitycznego na modyfikowanych Со-katalizatorach

Preferential adsorption of K species and the role of support during reforming of biomass derived producer gas over sulfur passivated Ni/MgAl2O4

Biomass gasification is a sustainable way to convert biomass residues into valuable fuels and chemicals via syngasproduction. However, several gas impurities need to be removed before thefinal synthesis. Understanding of the interactions andeffects of biomass-derived producer gas contaminants (S and K) on the performance of reforming catalysts is of great importancewhen it comes to process reliability and development. In the present study, the steam reforming activity at 800°C of a sulfur-equilibrated nickel catalyst during controlled exposure to alkali species (∼2 ppmv K) and in its absence was investigated using realproducer gas from a 5 kWthO2-blownfluidized-bed gasifier. Conversions of CH4,C2H4, and C10H8were used to evaluate theperformance of the Ni/MgAl2O4catalyst and MgAl2O4support. A significant and positive effect on the catalyst activity is observedwith addition of gas-phase KCl. This is assigned primarily to the observed K-induced reduction in sulfur coverage (θS)onNianeffect which is reversible. The catalytic contribution of the K-modified pure MgAl2O4support was found to be significant in theconversion of naphthalene but not for light hydrocarbons. The product and catalyst analyses provided evidence to elucidate thepreferential adsorption site for S and K on the catalyst as well as the role of the support. Whereas S, as expected, was found topreferentially adsorb on the surface of Ni particles, forming S-Ni sites, K was found to preferentially adsorb on the MgAl2O4support.A low but still significant K adsorption on S−Ni sites, or an effect on only the fraction of exposed Ni surface area near the metal−support interface, can, however, not be excluded. The result suggests that an improved Ni/MgAl2O4catalyst activity and anessentially carbon-free operation can be achieved in the presence of controlled amount of gas-phase potassium and high sulfurcoverages on Ni. Based on the results, a mechanism of the possible K−S interactions is proposedQC 20201019</p

Preferential adsorption of K species and the role of support during reforming of biomass derived producer gas over sulfur passivated Ni/MgAl2O4

Biomass gasification is a sustainable way to convert biomass residues into valuable fuels and chemicals via syngasproduction. However, several gas impurities need to be removed before thefinal synthesis. Understanding of the interactions andeffects of biomass-derived producer gas contaminants (S and K) on the performance of reforming catalysts is of great importancewhen it comes to process reliability and development. In the present study, the steam reforming activity at 800°C of a sulfur-equilibrated nickel catalyst during controlled exposure to alkali species (∼2 ppmv K) and in its absence was investigated using realproducer gas from a 5 kWthO2-blownfluidized-bed gasifier. Conversions of CH4,C2H4, and C10H8were used to evaluate theperformance of the Ni/MgAl2O4catalyst and MgAl2O4support. A significant and positive effect on the catalyst activity is observedwith addition of gas-phase KCl. This is assigned primarily to the observed K-induced reduction in sulfur coverage (θS)onNianeffect which is reversible. The catalytic contribution of the K-modified pure MgAl2O4support was found to be significant in theconversion of naphthalene but not for light hydrocarbons. The product and catalyst analyses provided evidence to elucidate thepreferential adsorption site for S and K on the catalyst as well as the role of the support. Whereas S, as expected, was found topreferentially adsorb on the surface of Ni particles, forming S-Ni sites, K was found to preferentially adsorb on the MgAl2O4support.A low but still significant K adsorption on S−Ni sites, or an effect on only the fraction of exposed Ni surface area near the metal−support interface, can, however, not be excluded. The result suggests that an improved Ni/MgAl2O4catalyst activity and anessentially carbon-free operation can be achieved in the presence of controlled amount of gas-phase potassium and high sulfurcoverages on Ni. Based on the results, a mechanism of the possible K−S interactions is proposedQC 20201019</p

Preferential adsorption of K species and the role of support during reforming of biomass derived producer gas over sulfur passivated Ni/MgAl2O4

Biomass gasification is a sustainable way to convert biomass residues into valuable fuels and chemicals via syngasproduction. However, several gas impurities need to be removed before thefinal synthesis. Understanding of the interactions andeffects of biomass-derived producer gas contaminants (S and K) on the performance of reforming catalysts is of great importancewhen it comes to process reliability and development. In the present study, the steam reforming activity at 800°C of a sulfur-equilibrated nickel catalyst during controlled exposure to alkali species (∼2 ppmv K) and in its absence was investigated using realproducer gas from a 5 kWthO2-blownfluidized-bed gasifier. Conversions of CH4,C2H4, and C10H8were used to evaluate theperformance of the Ni/MgAl2O4catalyst and MgAl2O4support. A significant and positive effect on the catalyst activity is observedwith addition of gas-phase KCl. This is assigned primarily to the observed K-induced reduction in sulfur coverage (θS)onNianeffect which is reversible. The catalytic contribution of the K-modified pure MgAl2O4support was found to be significant in theconversion of naphthalene but not for light hydrocarbons. The product and catalyst analyses provided evidence to elucidate thepreferential adsorption site for S and K on the catalyst as well as the role of the support. Whereas S, as expected, was found topreferentially adsorb on the surface of Ni particles, forming S-Ni sites, K was found to preferentially adsorb on the MgAl2O4support.A low but still significant K adsorption on S−Ni sites, or an effect on only the fraction of exposed Ni surface area near the metal−support interface, can, however, not be excluded. The result suggests that an improved Ni/MgAl2O4catalyst activity and anessentially carbon-free operation can be achieved in the presence of controlled amount of gas-phase potassium and high sulfurcoverages on Ni. Based on the results, a mechanism of the possible K−S interactions is proposedQC 20201019</p