Impact of residual fuel ash layers on the catalytic activation of K-feldspar regarding the water\u2013gas shift reaction

Katharina Fürsatz,Matthias Kuba,Daniel Janisch,Christoph Hammerl,Damian Chlebda,Kouessan Aziaba,Hermann Hofbauer,Joanna Łojewska

doi:10.1007/s13399-020-00645-w

Abstract

Interaction of biomass ash and bed materials in thermochemical conversion in fluidized beds leads to changes of the bed particle surface due to ash layer formation. Ash components present on the bed particle surface strongly depend on the ash composition of the fuel. Thus, the residual biomass used has a strong influence on the surface changes on bed particles in fluidized bed conversion processes and, therefore, on the catalytic performance of the bed material layers. Ash layer formation is associated with an increase in the catalytic activity of the bed particles in gasification and plays a key role in the operability of different biomass fuels. The catalytic activation over time was observed for K-feldspar used as the bed material with bark, chicken manure, and a mixture of bark and chicken manure as fuels. The changes on the bed material surfaces were further characterized by SEM/EDS and BET analyses. Raman, XPS, and XRD analyses were used to characterize the crystal phases on the bed material surface. An increase in surface area over time was observed for K-feldspar during the interaction with biomass ash. Additionally, a more inhomogeneous surface composition for fuels containing chicken manure in comparison to pure bark was observed. This was due to the active participation of phosphorus from the fuel ash in the ash transformation reactions leading to their presence on the particle surface. A decreased catalytic activity was observed for the same BET surface area compared to bark combustion, caused by the different fuel ash composition of chicken manure.Graphical abstractInteractions between fuel ash and K-feldspar increase the particle surface area and the catalytic activity regarding the water-gas-shift reaction

Highlights

Human activities since the age of industrialization are significantly influencing the Earth system, resulting in an environment that is less hospitable to the development of human societies
Steam gasification of biomass transforms the solid feedstock into a gaseous secondary energy carrier which enables the further production of electricity as net stabilizer, district heat, high-grade transportation fuels [5], pure hydrogen [6, 7], synthetic natural gas [8, 9], waxes, or synthetic chemicals [10]
A particular focus of this study lay in the characterization of the structure and composition of the ash layer formed upon biomass combustion and its further correlation with catalytic activity in the water–gas shift reaction

Summary

Introduction

Human activities since the age of industrialization are significantly influencing the Earth system, resulting in an environment that is less hospitable to the development of human societies. One of the main changes, where human action plays at least a significant part, is the rise of the global temperature [1]. The World Bank concluded that mitigating climate pollutants would at least significantly slow down the undesired climate change, which would decrease negative consequences for the human societies [2]. The thermochemical conversion of biomass, which is currently the main source of renewable energy globally [3], can Biomass Conv. Steam gasification of biomass transforms the solid feedstock into a gaseous secondary energy carrier which enables the further production of electricity as net stabilizer, district heat, high-grade transportation fuels [5], pure hydrogen [6, 7], synthetic natural gas [8, 9], waxes, or synthetic chemicals [10]. More details regarding the state of the art in steam gasification was provided by Karl and Pröll in 2018 [11]

Methods

Discussion

Conclusion