Effect of gas phase alkali species on tar reforming catalyst performance: Initial characterization and method development. (15th August 2015)

• Record Type: Journal Article
• Authors: Moud, Pouya H.; Andersson, Klas J.; Lanza, Roberto; Pettersson, Jan B.C.; Engvall, Klas
• Is Part Of: Fuel. Volume 154(2015)
• Page Start: 95
• Page End: 106
• Publication Date: 2015-08-15
• Subjects: Tar reforming -- Ni catalyst -- Biomass gasification -- Alkali -- Sulfur -- Potassium; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2015.03.027
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: A method to study gas alkali–catalyst interactions in real conditions is developed. Initial K uptake at low θK is approximately linearly proportional to time on stream. Indications of a slow approach to K equilibration on the catalyst were observed. Different KCl levels in the gas phase demonstrate different initial uptake of K. K adsorption suppression by sulfur was observed. Abstract: In thermochemical conversion of biomass to synthesis gas and biofuels, the effect of varying gas phase alkali concentrations on tar reforming catalyst performance in combination with gas phase sulfur and chlorine is largely unknown. The current study demonstrates a new methodology for investigating gas phase alkali adsorption and presents results for early stage adsorption on a Ni-based catalyst under realistic industrial conditions. The experiments were carried out using pine pellets as feedstock in a setup consisting of a 5 kW atmospheric bubbling fluidized bed gasifier, a high temperature hot gas filter and a catalytic reactor – all operating at 850 °C. A potassium chloride solution was atomized with an aerosol generator, and the produced submicrometer KCl particles were continuously introduced to the catalytic reactor where they rapidly evaporated to form KCl (g). The accurate dosing of gas-phase alkali was combined with elimination of transient effects in catalytic performance due to catalyst sintering and S adsorption, and results for K uptake in relation to sulfur uptake were obtained. Different KCl levels in the gas phase demonstrates different initial uptake of K on the catalyst surface, which at low K coverage ( θK ) is approximately linearly proportional to time on stream. The results also show a clear suppressing effect of sulfur adsorption on potassium uptake. Indications of a slow approach to K equilibration on the catalyst were observed. The potential of the developed methodology for detailed studies under close to industrial conditions is discussed.