Effect of pyrolysis temperature on the char micro-structure and reactivity of NO reduction

Abstract

A phenol-formaldehyde resin (PFR) and a bituminous coal (SH) were pyrolyzed at various temperatures. The structure and the char-NO reactivity were analyzed in order to examine the effect of pyrolysis temperature on the micro-structure of the resulting char and further on the reactivity towards NO. Micro-structure of the char samples was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy. It was indicated that the micro-structure of PFR char and coal char experienced remarkable changes during pyrolysis, which resulted in the decrease of phenolic OH, aromatic hydrogen and more ordered structure. The pyrolysis temperature showed a weak impact on the reactivity of PFR char but comparatively remarkable impact on that of coal char at lower reaction temperature. Mineral matter in coal char presented a weak effect on the reactivity.

Kinetics investigation on the reduction of NO using straw char based on physicochemical characterization

“…The results from EDS and XRD should provide an evidence for the sintering of straw char at a higher char-preparation temperature. The previous results of Yin et al (2009) obtained an optimal char-preparation temperature of 973 K with the largest surface area for the phenol-formaldehyde resin. Dong et al (2007) also found an optimal biomass preparation temperature in the range of 1073-1253 K, with the specific surface area of biomass char prepared at 1073 K greater than that of char prepared at higher temperatures.…”

“…Previous results of Yin et al (2009) also obtained an optimal char-preparation temperature for the highest NO reduction rate at 973 K; but the result of Dong et al (2007) indicated that with the char-preparation temperature increasing from 1073 to 1253 K the reduction rate of NO decreased, also providing an optimum ability to reduce NO for char prepared at 1073 K.…”

“…However, previous results have shown that there are still some obvious differences in the physicochemical characteristics and the reactivity of NO with biomass char and coal char (Dong et al, 2009b;Sahu et al, 2010;Vassilev et al, 2010;Wang et al, 2010a;Yin et al, 2009). Dong et al (2007Dong et al ( , 2009a determined the kinetics parameters for the reaction of NO and char in a fixed bed at 973-1173 K, which proposed the reaction order and the apparent activation energy to be, for straw-char, 0.66 and 114.40 kJ mol À1 , respectively, and for coal-char, 0.76 and 94.79 kJ mol À1 , respectively.…”

“…However, there are a number of studies indicating that the heterogeneous reduction of NO using biomass char is also noteworthy (Dong et al, 2007(Dong et al, , 2009aGarijo et al, 2003;Lin et al, 2010;Sun et al, 2009;Yin et al, 2009).…”

“…The effect of char-preparation temperatures on the microstructure and reactivity of NO and char has been conducted by Yin et al (2009). The phenol-formaldehyde resin char prepared at 973 K showed the best reactivity of NO reduction although there was little difference among the reactivity of the char prepared at 773, 873 and 1073 K. However, the results of Dong et al (2007) indicated the reactivity of NO reduction using biomass char decreased with the char-preparation temperature.…”