Kinetics of the steam gasification of a phenolic circuit board in the presence of carbonates

Steam gasification of a phenolic board in the presence of molten carbonate was studied as a means to recover useful metals effectively from electronic waste while also converting its plastic fraction into clean fuel gas. In the steam gasification of the phenolic board, the presence of carbonate considerably accelerated the conversion of tar and char into gaseous products. When pulverized phenolic board particles <0.15 mm were gasified, carbonate and steam permeated the sample particles, and the resulting gasification proceeded was well modeled by a homogeneous kinetic model. On the other hand relatively large phenolic board particles appeared to undergo two different hydrogen-producing gasification processes: the observed hydrogen formation rates suggest that an initial gasification occurred in the surface layer, which carbonate and steam were able to infiltrate into, and after this layer was consumed, the gasification proceeded only on the surface of the resulting char. The reactivity of char in the steam gasification depends sensitively on the conditions whereby the char is produced: rapid pyrolysis of the phenolic board produced highly reactive char, evidenced by markedly increased hydrogen formation rates in the steam gasification of chars formed under more rapid heating. However, once the char was pulverized finely, no obvious difference in reactivity was observed in the steam gasification based on the size of the phenolic board particles used to produce the char. (C) 2012 Elsevier Ltd. All rights reserved.