Fast Catalytic Pyrolysis of Tamarind Pulp over Green HZSM-5 Zeolite

Aiming to obtain chemicals from renewable sources to mitigate global warming, the catalytic pyrolysis of tamarind pulp, obtained from juice industries, was studied. Catalysts based on HZSM-5 zeolite prepared from rice husk ash using ultrasound, microwaves, and a combination of both were used. The catalysts were characterized by elemental analysis, X-ray diffraction, specific surface area and porosity measurements, scanning electron microscopy, and acidity measurements. The specific surface areas and the micropore volumes were slightly affected by the treatments, with microwave alone or combined with ultrasound having the strongest effect. The number of acid sites increased, and the relative number of strong sites decreased with the treatments. The relative amount of Bronsted to Lewis sites was increased by ultrasound and decreased by microwave, alone or combined. These catalysts decreased oxygenated products and increased BTEX production during tamarind pulp pyrolysis. Product distribution was similar for all cases, meaning that HZSM-5 with the following characteristics is a selective catalyst for BTEX in tamarind pulp pyrolysis: specific surface area = 310–347 m2/g; micropore volume = 0.099–0.105 cm3 g−1; acidity = 327 to 571 µmol NH3 gcat−1; and ratio of Bronsted to Lewis acid sites = 0.034 to 0.044.