Catalytic Hot Gas Cleanup of Biomass Gasification Producer Gas via Steam Reforming Using Nickel-Supported Clay Minerals

Ray Mark Bricka,Mark Zappi,Devin Peck,Prashanth Reddy Buchireddy

doi:10.3390/en14071875

Abstract

Amongst the issues associated with the commercialization of biomass gasification, the presence of tars has been one of the most difficult aspects to address. Tars are an impurity generated from the gasifier and upon their condensation cause problems in downstream equipment including plugging, blockages, corrosion, and major catalyst deactivation. These problems lead to losses of efficiency as well as potential maintenance issues resulting from damaged processing units. Therefore, the removal of tars is necessary in order for the effective operation of a biomass gasification facility for the production of high-value fuel gas. The catalytic activity of montmorillonite and montmorillonite-supported nickel as tar removal catalysts will be investigated in this study. Ni-montmorillonite catalyst was prepared, characterized, and tested in a laboratory-scale reactor for its efficiency in reforming tars using naphthalene as a tar model compound. Efficacy of montmorillonite-supported nickel catalyst was tested as a function of nickel content, reaction temperature, steam-to-carbon ratio, and naphthalene loading. The results demonstrate that montmorillonite is catalytically active in removing naphthalene. Ni-montmorillonite had high activity towards naphthalene removal via steam reforming, with removal efficiencies greater than 99%. The activation energy was calculated for Ni-montmorillonite assuming first-order kinetics and was found to be 84.5 kJ/mole in accordance with the literature. Long-term activity tests were also conducted and showed that the catalyst was active with naphthalene removal efficiencies greater than 95% maintained over a 97-h test period. A little loss of activity was observed with a removal decrease from 97% to 95%. To investigate the decrease in catalytic activity, characterization of fresh and used catalyst samples was performed using thermogravimetric analysis, transmission electron microscopy, X-ray diffraction, and surface area analysis. The loss in activity was attributed to a decrease in catalyst surface area caused by nickel sintering and coke formation.

Highlights

With an increasing global population comes an increase in energy demand
Another concern is related to fossil fuels in their possible depletion as well as the effect the industry has towards climate change
Naphthalene removal studies were conducted with different catalysts at 750 ◦ C, steam-to-carbon ratio (S/C)

Summary

Introduction

With an increasing global population comes an increase in energy demand. The global energy demand has been increasing by an annual average of 1.8% over the past 10 years [1].This demand is expected to increase by 15% from 2015 to 2030 and by an additional11% by 2040 [2]. The global energy demand has been increasing by an annual average of 1.8% over the past 10 years [1]. This demand is expected to increase by 15% from 2015 to 2030 and by an additional. Another concern is related to fossil fuels in their possible depletion as well as the effect the industry has towards climate change. Fossil fuel aerosols have been linked to an increase in surface temperature of 0.97 ◦ C during the same period [3]. Owing to the increasing energy demand and overwhelming evidence of the negative impact of fossil fuels with regard to climate change, there has been a push for alternative and renewable energy sources. In 2015, 4% of electricity came from renewable energy (RE) sources; the investment in RE technology continues to increase with a 14.1% increase in 2016 alone [1]

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Conclusion