The impact of metal type on the pyrolysis product distribution of sugar beet pulp: An analytical Py-GC/MS study with alumina-based catalysts

Abstract

The bio-oil produced by non-catalytic pyrolysis of biomass is typically corrosive and unstable due to the presence of several reactive components. Either in-situ or ex-situ catalytic models can be utilized with appropriate catalysts to achieve selective distribution of pyrolytic products during the catalytic pyrolysis of biomass, resulting in the generation of high-grade bio-oil. This study investigated the catalytic performances of different metal-incorporated alumina-based catalysts concerning the product composition in the pyrolysis of sugar beet pulp at 550 degrees C in a pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) system. Nitrogen adsorption, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques were used to characterize the metal-loaded alumina catalysts. FTIR analysis of catalysts with angular morphology proved the existence of alumina and metal-oxygen bonds (Me-O, Al-O, and Me-O-Al) in the structures, and x-ray diffraction patterns confirmed that crystalline phases were formed. It can be said that the crystal structures and functional groups determined by XRD and FTIR analyses had significant effects on the catalytic pyrolysis activity and product distribution. The main organic compounds obtained from the non-catalytic pyrolysis of sugar beet pulp were acids. In addition to acids, ketones, and aldehydes are among the undesirable compounds. As a result of catalytic pyrolysis, the lowest amount of aldehydes was generated when Ni-loaded alumina catalyst was employed. Notably, catalytic performances of Ni/Al2O3 and Co/Al2O3 resulted in the highest yields of valuable compounds in terms of hydrocarbons. The amount of undesired acidic compounds among the products, which increase the corrosive effect, was reduced by similar to 51 % compared to the non-catalytic pyrolysis result with the employment of the Fe/Al2O3 catalyst.