Photochemical synthesis of group 10 metal nanoclusters for electrocatalysis.

Four group 10 metal nanoclusters, Ni10(4-MePhS)20, Ni11(PhS)22, Pd9(PhS)18 and Pd10(PhS)20 were synthesized from disulfides based on a photochemical reduction-oxidation cascade process, which proceeds via a different mechanism to that of the conventional two-step reduction process. The as-obtained nanoclusters possess oxidative resistance and structural robustness under different conditions. Their atomically precise structures are determined to be nickel or palladium rings in which the metal atoms are bridged by Ar-S groups. Their catalytic performance in oxygen reduction reaction was compared, and the ring size-dependent catalytic activity of the group 10 metal nanoclusters was revealed. This work provides an efficient route to atomically precise and structurally stable group 10 metal nanoclusters, and sheds light on their further applications in electrocatalysis.

Upgrading of bio-oil via solar pyrolysis of the biomass pretreated with aqueous phase bio-oil washing, solar drying, and solar torrefaction.

In this study, three types of biomass were first pretreated with an aqueous phase bio-oil instead of traditional acid washing. Then, the washed samples were pretreated with drying (100 â„ƒ, 30 min) and torrefaction (250 â„ƒ, 30 min) using a parabolic-trough solar receiver system. The subsequent pyrolysis was performed at 550 â„ƒ for 10 min using a parabolic-dish solar receiver system. Results showed that the solar energy can effectively ensure the temperature required for biomass drying, torrefaction, and pyrolysis, having thus a potential to replace the conventional electric heating or fossil fuel heating. Such a strategy combines the advantages of the independent pretreatments, i.e., leaching out of metallic species and reduction of oxygen content. Consequently, the high heating value of bio-oil increased remarkably, the generation of acids was strongly inhibited, whereas the formation of phenols and anhydrosugars was promoted. Therefore, the method proposed herein is promising for upgrading of biomass and bio-oil.

Investigation of the relevance between biomass pyrolysis polygeneration and washing pretreatment under different severities: Water, dilute acid solution and aqueous phase bio-oil.

Washing pretreatments of rice straw were performed using three different solutions, namely water, dilute hydrochloric acid solution (HCl solution, pH = 2.9), and aqueous phase bio-oil (APBO, pH = 2.9). The raw and pretreated samples were pyrolyzed at 550 °C in a fixed bed reactor. Results showed that among the three pretreatments, washing with APBO had the highest removal efficiency of alkali metal and alkaline earth metals (AAEMs). Among the pyrolysis products, bio-oil from APBO washed sample had the highest mass, energy, and carbon yields, lowest water content of 36.9%, highest HHV of 17.2 MJ/kg, and highest relative content of anhydrosugars of 31.2%. Its biochar had the lowest ash content of 27.3% and highest specific surface area of 98.6 m2/g, and its non-condensable gases had the highest HHV of 11.9 MJ/m3. Therefore, APBO washing was effective in improving the quality of biomass and its subsequent pyrolysis products.

An approach for upgrading biomass and pyrolysis product quality using a combination of aqueous phase bio-oil washing and torrefaction pretreatment.

Bio-oil undergoes phase separation because of poor stability. Practical application of aqueous phase bio-oil is challenging. In this study, a novel approach that combines aqueous phase bio-oil washing and torrefaction pretreatment was used to upgrade the biomass and pyrolysis product quality. The effects of individual and combined pretreatments on cotton stalk pyrolysis were studied using TG-FTIR and a fixed bed reactor. The results showed that the aqueous phase bio-oil washing pretreatment removed metals and resolved the two pyrolysis peaks in the DTG curve. Importantly, it increased the bio-oil yield and improved the pyrolysis product quality. For example, the water and acid content of bio-oil decreased significantly along with an increase in phenol formation, and the heating value of non-condensable gases improved, and these were more pronounced when combined with torrefaction pretreatment. Therefore, the combined pretreatment is a promising method, which would contribute to the development of polygeneration pyrolysis technology.

Pyrolysis polygeneration of poplar wood: Effect of heating rate and pyrolysis temperature.

The pyrolysis of poplar wood were comprehensively investigated at different pyrolysis temperatures (400, 450, 500, 550, and 600°C) and at different heating rates (10, 30, and 50°C/min). The results showed that BET surface area of biochar, the HHV of non-condensable gas and bio-oil reached the maximum values of 411.06m(2)/g, 14.56MJ/m(3), and 14.39MJ/kg, under the condition of 600°C and 30°C/min, 600°C and 50°C/min, and 550°C and 50°C/min, respectively. It was conducive to obtain high mass and energy yield of bio-oil at 500°C and higher heating rate, while lower pyrolysis temperature and heating rate contributed towards obtaining both higher mass yield and energy yield of biochar. However, higher pyrolysis temperature and heating rate contributed to obtain both higher mass yield and energy yield of the non-condensable gas. In general, compared to the heating rate, the pyrolysis temperature had more effect on the product properties.