Influence of Nickel Modified Beta Zeolite in the Production of BTEX During Analytical Pyrolysis of Medium-Density Fiberboard (MDF)

Abstract

Production of high added value chemicals such as BTEX by means of catalytic fast pyrolysis of MDF residues is a promising and environmentally friendly alternative to fossil fuels, as MDF is abundantly produced worldwide. Generation of toxic compounds during MDF pyrolyses was minimized with pre-treatments with yeasts or hot water resulting in a maximum removal of 87.9% of nitrogen compounds when water was used at 80 °C, for 3 h. Nickel-modified beta zeolites with 3 (Ni3B-H) and 5 wt% of nickel (Ni5B-H) were more efficient for the production of BTEX compounds (Ni3B-H: 39.35% and Ni5B-H: 38.65%) and reduction of polyaromatic hydrocarbons (Ni3B-H: 11.12% and Ni5B-H: 15.93%) when compared to pure beta zeolite. Non-catalytic pyrolysis resulted only in oxygenated compounds. These findings were related to the changes of the crystallographic sites of aluminum and then on acidic sites, as well as to the production of a bifunctional catalyst during reactions.

Thermokinetic and Thermodynamic Parameters for Catalytic Pyrolysis of Medium Density Fiber over Ni/Beta Zeolite

“…Also, nickel contents were higher than expected, indicating that some zeolite was lost during nickel impregnation. In addition, the samples showed high specific surface areas, which is consistent with previous work [9]. After nickel impregnation, no change in this parameter was noted and the observed differences were within the experimental error.…”

“…The catalyst slightly shifted the DTG peak to higher temperatures compared to non-catalytic pyrolysis, suggesting a change in the reaction pathways. As found by Mayer et al (2022), studied the MDF decomposition over beta zeolite obtained from commercial silica, catalytic pyrolysis produced mostly high-value aromatics (benzene, toluene, xylenes and ethylbenzene), whereas non-catalytic pyrolysis produced only oxygenated compounds [9]. the DTG peak temperatures of the samples were summarized in Table 2.…”

“…The formation of the beta zeolite was confirmed by X-ray diffraction. For all cases (Figure S1), peaks at 8° and 22° were detected, which are characteristic of the zeolite structure [9,10]. All samples showed the same X-ray diffraction pattern and those containing nickel showed an increase in intensity at 44°, due to the overlap of nickel and zeolite peaks.…”

“…The method of pre-treatment, as well as the chemical composition of MDF residues (M sample) were described in previous work [9]. Before the pyrolysis experiments, the pretreated biomass was dried at 40°C for 12 h and the particles ranging in size from 0.25 to 0.43 mm (40-60 mesh) were selected for the experiments.…”

“…Among the catalysts proposed for pyrolysis, zeolites have been considered as the most efficient ones, due to their high specific surface area, multiple channel system, high acidity and shape selectivity [8]. Beta zeolite, for instance, is highly selective to benzene, toluene, ethylbenzene, and xylenes (BTEX) [9], which are high-value chemicals in several industrial processes [9]. In addition, it has high catalytic activity, selectivity, and resistance to deactivation, in various reactions such as cracking, alkylation and acylation of aromatic hydrocarbons and hydroisomerization of alkanes [10,11].…”