The production of hydrogen and syngas (H2/CO) from waste tires by pyrolysis catalytic steam reforming was investigated in a two-stage fixed bed reactor. In this study, tire char served as a sacrificial catalyst, facilitating the combination of catalytic steam reforming and char steam gasification reactions. The tire char acted as both a catalyst and a gasification reactant, enhancing the gas product yield. The process parameters investigated were, a reforming temperature range of 700–1000 °C, steam space velocity between 2 and 12 g h−1 g−1char and reaction times of 0.5–2 h. The influence of the parameters on the yield and composition of the product gases and the characteristics of the used catalyst were analyzed in detail. The results indicated that higher temperature and steam space velocity increased H2 and CO yields in the presence of a tire char catalyst. Elemental analysis of the used tire char, surface morphology and pore structure provided insights into the extent of tire char consumption in the reaction. Prolonged reaction time allowed for more thorough reactions between the pyrolysis volatiles and tire char, promoting the production of H2. At a reaction time of 2 h, the H2 yield reached 223 mmol g−1, representing 74 wt% of the maximum hydrogen yield.

Pd nanocatalyst supported on amine-functionalized mesoporous graphitic carbon nitride (Pd/NH2-mpg-C3N4) was investigated for dehydrogenation of formic acid. The catalyst was analyzed and tested to investigate the effect of amine functionalization on hydrogen generation from formic acid. Pd nanocatalyst was dispersed uniformly on NH2-mpg-C3N4 without agglomeration. The turnover frequency value of Pd/NH2-mpg-C3N4 was 1870 h−1, which was higher than that of Pd/mpg-C3N4 because of the amine functionalization. The Pd/NH2-mpg-C3N4 was also tested to investigate the effect of various reaction conditions (formic acid concentration, sodium formate concentration, and reaction temperature) on hydrogen generation from formic acid. Formic acid concentration negatively affected the catalytic activity, whereas sodium formate concentration positively affected it. Reaction temperature significantly affected the catalytic activity. The apparent activation energy of the Pd/NH2-mpg-C3N4 catalyst was 60.7 kJ mol−1, and a hydrogen generator with the catalyst exhibited high conversion efficiency at an elevated temperature. Consequently, a hydrogen generator with Pd/NH2-mpg-C3N4 is suitable for polymer electrolyte membrane fuel cell systems.

The additivation of solid biofuels has proven to be an effective method for reducing total particulate matter (TPM) and carbon monoxide (CO) emissions, as well as for reducing ash-related problems related to, e.g., fouling and slagging. During the combustion with additives, potassium (K) released from the solid biofuels is bound into temperature-stable compounds, thus preventing the formation of inorganic (i.e., K-based) TPM. Simultaneously by reducing K in the gas phase, the inhibition of gas-phase oxidation (e.g., CO oxidation) due to interference of K within the existing radical pool is hindered. Particularly kaolin, an aluminum-silicate-based additive has proven effective in reducing not only TPM but also CO emissions. The mitigation effects on CO emissions have previously been reported mostly in a subordinate role and explanations are given in the form of hypotheses. In this study, seven additives (i.e., kaolin, kaolinite, meta-kaolinite, aluminum hydroxide, muscovite, muscovite coated with titanium dioxide and kalsilite, each at 0.3 wt%a.r.) were investigated during wood pellet combustion in a small-scale furnace (7.8 kW). For both CO and TPM emissions, kaolin proved to be most effective (i.e., −52% CO, −49% TPM), followed by muscovite, kaolinite, TiO2 coated muscovite, aluminum hydroxide, and meta-kaolinite.