Effects of Temperature and Heating Rate on the Characteristics of Molded Bio-char

A slow pyrolysis of pinewood was investigated in this paper. Through the briquette process, the pinewood sawdust becomes molded biomass. The molded bio-char was produced from molded biomass with different pyrolysis factors, and the bio-char’s heating value, char yield rates, and physicochemical and morphological properties were investigated. Molded bio-char’s characteristics depended principally on pyrolysis factors. At low temperature (400 °C), the char yield rate was positively correlated to the heating rate. But at higher temperatures (500 to 700 °C), the char yield rates decreased as heating rates increased. As pyrolysis temperature increased from 400 to 700 °C, the following increased in molded bio-char: fixed-carbon content, percentage carbon, heating value, ash content, as well as surface areas. And its pore structure, graphite degree, and polymerization degree achieved a higher level. Compared with pulverized bio-char, the molded bio-char had a higher char yield rate, ash content, graphite degree, and structure ordering. The molded bio-char obtained from a low temperature (400 °C) and high heating rate (15 °C/min) can be used as a reducing agent, the molded bio-char from 600 °C is recommend as an activated carbon precursor, and the molded bio-chars from low temperature (400 °C) have a higher efficiency as fuel.