The release of chlorine (Cl) and sulfur (S) during biomass torrefaction and pyrolysis has been investigated via experiments in two laboratory-scale reactors: a rotating reactor and a fixed bed reactor. Six biomasses with different chemical compositions covering a wide range of ash content and ash-forming elements were torrefied/pyrolyzed in the temperature range of 150−500 °C. The relative release of chlorine and sulfur was calculated based on mass balance and analysis of the biomass before and after torrefaction. In selected cases, measurement of methyl chloride (CH 3 Cl) in the gas from straw torrefaction has furthermore been conducted. The release of chlorine from straw was first observed at 250 °C and peaked with about 60−70% at 350 °C. Analysis of the released gas showed that most of the chlorine was released as methyl chloride. Increasing the straw content in the reactor resulted in a lower fractional release of Cl, probably due to more reactive sites in contact with gas phase Cl species leading to secondary binding of Cl to the solid product. Almost complete release of chlorine was observed for woody biomass at 350 °C. This result is in agreement with previous studies reporting that biomasses with a lower chlorine content release a higher fraction of chlorine during the pyrolysis process. A significant sulfur release (about 60%) was observed from the six biomasses investigated at 350 °C. The initial sulfur content in the biomass did not influence the fraction of sulfur release during torrefaction.

Different biomass types may differ with respect to torrefaction characteristics, and an improved understanding and ability to predict the torrefaction performance is, therefore, desired. In this study, the influence of the chemical properties (lignocellulose composition and alkali content) on the torrefaction behavior with respect to mass loss and grindability is investigated by simultaneous thermal analysis (STA) and by using a combined torrefaction and grinding reactor. The torrefaction behavior of six raw biomass samples and selected pretreated samples (washed and impregnated with KCl and K2CO3) has been studied. The investigated biomasses have reasonably similar carbohydrate compositions (hemicelluloses 18–25 wt % db; cellulose 38–48 wt % db; lignin 17–29 wt % db) with the exception of spruce bark, which is lower in hemicellulose content (12.9 wt % db) and cellulose content (24 wt % db), and higher in lignin content (36.8 wt % db). An increasing biomass potassium (K) content decreases the temperature of maximal conversion for both raw and alkali-impregnated biomass samples, thus decreasing the solid product yield at 270 and 300 °C. This was especially pronounced when the biomass potassium content increased from 0 to 0.2 wt %. However, the higher lignin content in bark causes a higher solid yield than what would be expected from the alkali content, illustrating that both potassium content and lignocellulose composition affect the solid yield obtained by torrefaction. The grindability of the torrefied products was evaluated by determining the d50 value of the particle size distribution of the biomass before and after torrefaction in the combined torrefaction and mill reactor. A significant decrease in d50 value was observed when the alkali content increased from 0 to 0.2 wt % db, whereas no additional effect is seen for higher potassium contents.

8Platinum-based oxidation catalysts applied for diesel exhaust aftertreatment constitute a significant part of 9 system costs. Effective utilization of platinum is therefore relevant to reduce costs while retaining 10 performance. To this end, the influence of Pt particle size on catalytic activity for CO, hydrocarbon, and NO 11 oxidation was studied. 1 wt.% Pt/Al2O3 catalysts were prepared by wet impregnation, drying, and different 12 calcination and thermal treatments, yielding Pt particles with diameters between 1.3 and 18.7 nm, as 13 determined by CO pulse titration and transmission electron microscopy. Activity measurements for CO, C3H6, 14 and NO oxidation showed an optimal Pt particle size with respect to the mass based activity between 2-4 nm 15 for all three reactions. From measured turnover frequencies and site statistics of Pt particles, the reactions 16 appear to be mainly catalyzed by terrace atoms, which are most abundant between 2-4 nm. The decrease in 17 catalytic activity for large Pt particles is therefore due to the diminishing Pt surface area, while the decrease in 18 activity for small particles is due to the lack of terrace atoms required for CO, HC, and NO oxidation.

The objective of this work is to study the influence of particles, electrolytes, and buffers on the foaming ability of wet flue gas desulfurization (FGD) slurries. Foaming within this industrial process has been associated with a range of operational problems, as well as an increased degree of absorption. The foaminess of selected process parameters has been assessed, systematically, using laboratory-scale Bikerman experiments. Adipic acid alone, as well as a combination of small particles and an electrolyte, have been demonstrated to generate weak transient foams (with a Bikerman coefficient (Σ) of e7 s), that potentially can interfere with process monitoring equipment. Additional experiments with a wet FGD pilot plant showed an increased absorption efficiency of sulfur dioxide (SO 2 ) by a tap water solution with small quartz particles and calcium chloride (CaCl 2 ), compared to a solution of pure tap water.

Combining torrefaction and grinding of biomass in one reactor may be an attractive fuel pretreatment process. A combined laboratory torrefaction and ball mill reactor has been constructed for studies of the influence of temperature and residence time on the product yields and particle size reductions of Danish wheat straw, spruce chips, and pine chips. On the basis of initial experiments, which evaluated the influence of reactor mass loading, gas flow, and grinding ball size and material, a standard experimental procedure was developed. The particle size reduction capability of the torrefaction process has been evaluated by the relative change in d 50, and this method was compared to the Hardgrove grindability index (HGI), showing reasonably similar results. Significant differences in torrefaction behavior have been observed for straw and spruce chips torrefied at 270–330 °C. Torrefaction of straw for 90 min yielded a higher mass loss (27–60 wt %) and relative size reduction (59–95%) compared with spruce (mass loss of 10–56 wt % and size reduction of 20–60%). The two types of biomass investigated differ with respect to hemicellulose type, lignocellulosic composition, particle morphology, and ash composition, where straw has a higher alkali content. This and other studies indicate that the large difference in the alkali contents of the biomasses is the main cause for the observed difference in torrefaction characteristics. Experiments with separate particle heating and grinding showed a swift grinding of the torrefied biomass. This implies that the rate-limiting step in the laboratory reactor is the heat transfer and not the grinding process. Large pine particles (8–16 mm) showed a slightly higher mass loss than 4–8 and <4 mm particles. This could be the consequence of exothermic reactions in the particle core, which locally increase the temperature and conversion.