Carbon Resources Conversion最新文献

Conversion of delignified cellulose from rice husk biomass, and model compounds of cellobiose and glucose to levulinic acid (LA) over hierarchical Mn₃O₄/ZSM-5 catalyst was carried out using a household microwave method, and then compared to the established conventional thermos-reaction method. The hierarchical ZSM-5 was prepared using a double template method, aiming for micro and mesoporous systems developed in the structure. The as-prepared ZSM-5 were modified with Mn₃O₄ through incipient wetness impregnation with Mn²⁺ solution followed by calcination at 550 °C. The catalysts were characterized using various techniques such as powder XRD, SEM, BET, AAS, and FT-IR which indicated the hierarchical structure of MFI zeolite (Si/Al of 30–34) with Mn loading of 2.14 wt%. The conversion products were analyzed using HPLC, ¹H NMR, and ¹³C NMR instruments. The microwave-assisted reaction using 600 W for 180 s using delignified cellulose, cellobiose, and glucose gave conversion of 37.27%, 46.35%, and 54.29%, respectively which is close to the conversion given by the conventional reaction carried out at 130 °C for 4 h (36.75%, 55.62%, and 60.9%, respectively). Interestingly, the LA yield from the microwave-assisted reaction (4.33%, 6.12%, and 9.57%) is higher than the yield from the conventional reaction, which only produced 5.2%, 4.88%, and 6.93% respectively. The microwave-assisted method is also shown to give less by-products compared to the thermochemical reaction. Therefore, it could be considered an alternative method for converting cellulose to LA.

The purpose of this study is to explore a method for the high-yield production of hydrogen by pyrolysis and steam reforming of polymer plastics. The developed Fe-based catalyst supported on activated carbon was applied to reactions with polypropylene for hydrogen production. The effects of iron loading (%) in the catalyst, the total catalyst amount, and the water content in the reaction atmosphere on the performance of hydrogen and gas production were investigated. Under the optimal conditions, the hydrogen yield without water added reached 38.73 mmol/g_PP, and this yield was significantly improved by adding water into the reaction atmosphere. By optimizing the amount of water added, the hydrogen yield reached 112.71 mmol/g_PP. The surface morphology and structural components of the fresh and used catalysts were characterized, and the morphology and quantity of carbon deposition on the catalyst were analysed. The catalytic stability of the 15Fe/AC catalyst was determined by repeating the test 10 times under the optimal reaction conditions. As the reaction time increased, the selectivity of the catalyst for hydrogen decreased and that for hydrocarbons increased. Moreover, the experimental method used in this study had excellent hydrogen production capacity. Thus, this study provided a novel method for the high-efficiency production of hydrogen by pyrolysis and steam reforming of polymer plastics.

The performance degradation mechanism of ceramic fuel cell with NCAL (Ni_0.8Co_0.15Al_0.05LiO₂) as symmetrical electrode and GDC as electrolyte in H₂ is investigated. It is found that under the condition of 550 °C and constant current density of 0.2 A·cm⁻², the output voltage of the cell is about 1.005 V in the initial 10 h and remains relatively stable. After 10 h, the voltage of the cell began to decrease gradually, and by 50 h, the voltage had decreased to 0.522 V. The results testing electrochemical performance of the cell and characterizing the cell materials before and after test using SEM, TOF-SIMS and FTIR indicate that the distribution of Li₂O/LiOH/Li₂CO₃ compounds generated from NCAL anode in the cell plays a vital role in significantly improving the ionic conductivity of electrolyte and gas tightness of the cell. The dynamic migration of molten salt destroyed the continuity of molten salt in the cell, which in turn adversely impacted the ionic conductivity of electrolyte, gas tightness of the cell, and electrochemical reactions on both sides of the cathode and anode. These finally lead to the degradation of the cell performance.

The method to increase PtRu utilization and its catalytic activity of PtRu nanoparticles supported on reduced graphene oxide (RGO) by avoiding its restacking was proposed with the aim of developing an active catalyst for a direct methanol fuel cell. The heat treatment at 200 °C of the GO aerogel (GOA) prepared by freeze drying of GO ice was introduced to weaken the attractive force of the hydrogen bonding between the GO sheets followed by the composite with the nanoparticles, i.e., ketjenblack (KB), TiO₂ and Ti₄O₇, at different weight ratios. The catalyst supported on the heat-treated GOA (RGOA), PtRu/RGOA, improved the PtRu utilization to some extent and also increased the ECSA and mass activity compared to that of PtRu/RGO. RGOA had fewer oxygen functional groups, especially the epoxy groups. Due to the treatment and composite, the PtRu utilization was increased from 66.5% for PtRu/RGO to 128.6 % for PtRu/RGOA + Ti₄O₇ (4:1) and the mass activity was improved from 50.7 A/g-_PtRu for PtRu/RGO to 130.5 A/g-_PtRu for PtRu/RGOA + Ti₄O₇ (1:1). The Ti₄O₇ nanoparticles showed the best catalytic performance for the composite suggesting that the strong interaction between Ti₄O₇ and the Pt nanoparticles was effective due to its high electronic conductivity.

The steam gasification characteristics of poplar sawdust were investigated in a piston fed fixed-bed gasifier, reflecting the batch feeding process of fixed-bed gasifiers in industrial applications. The effects of operating conditions, including steam supply, the flow rate of inert gas, gasification temperature, and feeding rate, on gasification reactivity and performance were investigated online. The major gas product during pyrolysis was CO, followed by H₂, CH₄, and CO₂, and the gasification was greatly facilitated by the injection of steam to generate H₂. The gasification reactivity and performance were improved with increased steam supply and temperature. The maximum production rate of H₂ by char gasification was tripled and doubled, respectively, with an increase in steam supply from 50 to 400 mL/min and a temperature rise from 800 to 900 °C, and the time required for complete gasification was also halved. Compared to pyrolysis, the volume fraction of H₂ increased from 23% to 37%, and correspondingly, the H₂/CO ratio increased from 0.42 to 0.95.

This paper proposes a comprehensive summary and analysis of an important issue during municipal solid waste (MSW) gasification-sulfur and nitrogen pollution. It provides an overview of the fundamentals of MSW and the basic aspects of nitrogen and sulfur elements. Their characteristics of immigration, transformation and distribution during gasification with control solutions in realized or potential engineering are also concluded. The analysis indicates that the complete scenario of the occurrence form of sulfur and nitrogen elements in MSW is difficult to obtain, owing to the diverse sources and complicated compositions. However, with the assistance of advanced characterization and quantification methods (XPS, XRD, TG-FTIR, et al.), the common sulfur- and nitrogen-containing compounds in both organic and inorganic states can be detected. Adjustment of gasification conditions can regulate the transformation of these elements for emission control. The multiple pollutants including H₂S, SO_x, COS, NH₃, HCN and NO_x cannot be eliminated by one-step treatment but a combination of adsorption and catalytic treatments may realize the control goal. This research aims to benefit meeting emission standards during MSW gasification and to provide a reference for other processes such as incineration, pyrolysis and other feedstocks like biomass and refuse derived fuel (RDF).

The three-dimensional (3D) self-supporting Pt nanoflower catalyst was prepared by using Pt organic compounds as precursors in a low-temperature molten salt system. The obtained Pt nanoflower nanoparticle can reach 400–500 nm with a face-centered cubic structure, which has the structural characteristics of a loose framework and more exposed active sites. The surfactant-free Pt nanoflower was directly used as methanol electrooxidation reaction (MOR) electrocatalysts without any pretreatment and activated carbon support. The results of electrochemical catalytic oxidation of methanol showed that the Pt nanoflower catalyst exhibit more enhanced electrocatalytic oxidation performance toward methanol compared with the commercial platinum black catalyst. The green and effective method can be developed and expected to enable mass production of fuel cell catalysts.

Five agro-industrial residues, their corresponding spent mushroom substrates (SMS), commercial fresh and spent mushroom compost of Agaricus (SMC) and Pleurotus ostreatus (SMS GZ) cultivation, Pleurotus and Agaricus waste (stipes/mishappen mushrooms) were combined and re-utilized as novel substrates for the cultivation of P. ostreatus, P. eryngii and A. bisporus mushrooms. SMSs/ SMC were used up to 40% (treatment 1 and 2), while 20% of mushroom waste were added in fresh and spent substrates (treatment 3 and 4). The impact of different substrates on mycelial growth rate and biomass production was examined. Then, Pleurotus spp. were cultivated on the most promising substrates and essential cultivation aspects (earliness, total mushroom yield, biological efficiency-BE) and carposomes’ quality parameters (weight, morphological characteristics) were evaluated. Laccase and endoglucanase production by Pleurotus species were also determined at 50 and 100% of colonization stages. All species showed their fastest mycelial growth rate (up to 5 mm/day) on substrates consisted of SMC, whereas many combinations of species/substrate enhanced biomass production. The SMS GZ supplementation positively affected laccase activity; in the cultures of P. ostreatus and P. eryngii the highest values were 62,539 and 17,584 U/g d.w., respectively. On the contrary, small amounts of endoglucanase were produced (0.007 to 0.322 U/g d.w.); the greatest production was recorded for P. ostreatus at full colonization. Regarding fermentation in bags, significant amount of total mushroom yield was produced in all substrates and those with SMS GZ supported the fastest earliness period and the highest BE for both Pleurotus species. BE values ranged from 54 to 133% for P. ostreatus and from 53 to 121% for P. eryngii. Concerning morphological characteristics, mushroom waste addition seemed to affect them positively. The data included in this paper support the effective re-utilization of different types of SMS and mushroom waste for fungal mass and enzymes’ production and for new high quality Pleurotus spp. carposomes.

Single Cell Protein (SCP) refers to dry cells of microorganisms, and it constitutes a highly promising and alternative protein source for multiple applications. SCP presents a rich nutritional profile containing valuable amino acids and fatty acids, nucleic acids, minerals, and several vitamins. Several businesses worldwide have introduced SCP into their production cycles, hence expanding the scope of its application in value added market chains such as the edible food packaging. SCP is produced by a plethora of microorganisms, including fungi, yeasts, bacteria, and algae while many of them are Generally Recognized as Safe (GRAS). Selected microbial strains present satisfying growth capability with high yields when cultivated in renewable feedstock. Thus, production rates and process sustainability could be enhanced via the valorization of industrial and agricultural wastes as the nutrient sources, combined with optimization of process parameters, i.e fermentation mode and feeding strategy, pH, temperature, C/N ratio, agitation rate and oxygen supply. This review addresses the latest developments made towards the SCP production, highlighting efficient microbial SCP producers, and production systems that valorize solid and liquid streams from several agricultural wastes. Potential applications, challenges in sensorial-, and safety-aspects as well as consumers perception issues of SCP incorporation into food-related matrices are also discussed.