Impact of Biomass and Main Biomass Components on Coal Reactivity under Oxy-Combustion Conditions—A Comparison of Physicochemical Char Properties Obtained under N₂ and CO₂ Atmospheres

Abstract

In the present study, wood biomass from Acacia mangium and its main components (hemicellulose (xylan), cellulose, and lignin) were blended with a sub-bituminous coal in 20:80 wt % ratio and subsequently were heat-treated at 900 °C using CO2 or N2 atmospheres. The reactivity (ignition temperature and activation energy) under oxy-fuel conditions (21% O2–79% CO2) was studied by thermogravimetry (TGA). It has been observed that adding biomass or its main components to coal improved the combustion efficiency. Coal/biomass and coal/xylan/cellulose/lignin char blends showed lower ignition temperatures when they were devolatilized using CO2 instead of N2. In addition, the activation energies were lower for blends thermally treated with CO2. Differences in reactivity are discussed considering changes in physical-chemical properties characterized by SEM, N2 adsorption at −196 °C, Raman spectroscopy, and XPS.

Potassium Catalytic Effect on Gasification Reactions of Coal and Coal/Biomass Blends under Oxy-combustion Conditions. An Isotopic Study Using 13C18O2

“…This behavior suggests that the presence of potassium during the thermal process accelerates the cracking degree of the amorphous carbon fraction; therefore, the graphitization signal diminishes considerably. These results are in agreement with our previous work 26 .…”

“…Oxy-combustion reactivity tests were carried out in a thermogravimetric analyzer (SDT Q600-TA Instruments) following the same methodology reported in a previous work …”

“…Oxy-combustion reactivity tests were carried out in a thermogravimetric analyzer (SDT Q600-TA Instruments) following the same methodology reported in a previous work 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Aldrich and 16 O 2 (99.999 %) was provided by Abelló-Linde. Experiments were carried out in a quartz fixed bed microreactor with an internal diameter of 5 mm using 150 mg of impregnated samples (CIK and C/BIK).…”

“…Therefore, an inhibition of K 2 CO 3 reduction to more active intermediates in C/BIK materials under both pre-treatment atmospheres (N 2 and CO 2 ) could occur increasing the activation energy values during the oxy-combustion process as it was observed. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 The activation energies showed in Table 6, were determined using the non-isothermal thermogravimetric method and treating the obtained data under the mathematical model of the maximum speed, as indicated in our previous study 26 . Before determination of kinetic values, tests for avoiding diffusional effects were evaluated.…”

A Comprehensive Review on Thermal Coconversion of Biomass, Sludge, Coal, and Their Blends Using Thermogravimetric Analysis

“…Recently, Kandasamy Jayaraman et al studied coal and biomass blends and they concluded that by increasing the ratio of biomass in the blends, the mass loss percentage increases, indicating the high reactivity of samples, and the activation energies were also increased by increasing biomass ratio in the blends [57]. Betancur et al studied that coal and biomass blends increased combustion efficiency [124]. Blends showed lower ignition temperatures, and activation energies were decreased in the CO 2 environment as compared to N 2 .…”