Zhiqi Wang

Bio: Zhiqi Wang is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Chemical looping combustion & Oxygen. The author has an hindex of 17, co-authored 38 publications receiving 849 citations. Previous affiliations of Zhiqi Wang include Qingdao University of Science and Technology.

Low Temperature Pyrolysis Characteristics of Oil Sludge under Various Heating Conditions

Abstract: Pyrolysis of oil sludge first by thermogravimetry/mass spectroscopy (TG/MS) and then in a horizontal quartz reactor with an electrical laboratory furnace under different pyrolysis conditions was carried out. The influence of heating rate from 5 to 20 °C·min-1, final pyrolysis temperature from 400 to 700 °C, various interval holding stage, and catalyst on the products were investigated in detail. The TG/MS results show that pyrolysis reaction of oil sludge starts at a low temperature of about 200 °C, and the maximum evolution rate is observed between the temperatures of 350−500 °C. A higher final pyrolysis temperature, an interval holding stage, and adding catalyst can promote the pyrolysis conversion (in terms of less solid residue production). In all parameters, an interval holding stage for 20 min near the peak temperature of 400 °C can enhance the yield of oil and improve its quality. Three additives used in this work as catalysts do not improve oil product quality markedly in spite of increasing pyrol...

Construction of a Z-scheme heterojunction for high-efficiency visible-light-driven photocatalytic CO2 reduction

Abstract: The continuous growth of fossil fuel consumption and large amounts of CO2 emissions have caused global energy crisis and climate change. The employment of semiconductor photocatalysts to convert CO2 into value-added products has attracted extensive attention and research worldwide in recent years. However, it is difficult for a single-component semiconductor photocatalyst to achieve this goal efficiently due to its drawbacks, such as low quantum efficiency, limited surface area, limited number of active sites, the short lifetime of photogenerated carriers, poor long-term stability, and the weak redox ability of carriers. Fortunately, inspired by photosynthesis, the construction of an artificial Z-scheme heterojunction has brought a new dawn for the realization of this goal. The Z-scheme heterojunction has a high separation efficiency of electron-hole pairs with strong redox ability and a wide light response range. The abovementioned advantages make the Z-scheme heterojunction provide a great opportunity for the conversion of CO2 to value-added chemicals. This review concisely reports the progress of the Z-scheme heterojunction in the field of photocatalytic CO2 reduction in recent years, photocatalytic mechanism, choice of oxidation and reduction systems, strategies for improving efficiency, confirmation of the Z-scheme charge transport mechanism, problems and challenges, and the prospects for the future.

A comparative overview of hydrogen production processes

Abstract: Climate change and fossil fuel depletion are the main reasons leading to hydrogen technology. There are many processes for hydrogen production from both conventional and alternative energy resources such as natural gas, coal, nuclear, biomass, solar and wind. In this work, a comparative overview of the major hydrogen production methods is carried out. The process descriptions along with the technical and economic aspects of 14 different production methods are discussed. An overall comparison is carried out, and the results regarding both the conventional and renewable methods are presented. The thermochemical pyrolysis and gasification are economically viable approaches providing the highest potential to become competitive on a large scale in the near future while conventional methods retain their dominant role in H2 production with costs in the range of 1.34–2.27 $/kg. Biological methods appear to be a promising pathway but further research studies are needed to improve their production rates, while the low conversion efficiencies in combination with the high investment costs are the key restrictions for water-splitting technologies to compete with conventional methods. However, further development of these technologies along with significant innovations concerning H2 storage, transportation and utilization, implies the decrease of the national dependence on fossil fuel imports and green hydrogen will dominate over the traditional energy resources.

An overview of advances in biomass gasification

Abstract: Biomass gasification is a widely used thermochemical process for obtaining products with more value and potential applications than the raw material itself. Cutting-edge, innovative and economical gasification techniques with high efficiencies are a prerequisite for the development of this technology. This paper delivers an assessment on the fundamentals such as feedstock types, the impact of different operating parameters, tar formation and cracking, and modelling approaches for biomass gasification. Furthermore, the authors comparatively discuss various conventional mechanisms for gasification as well as recent advances in biomass gasification. Unique gasifiers along with multi-generation strategies are discussed as a means to promote this technology into alternative applications, which require higher flexibility and greater efficiency. A strategy to improve the feasibility and sustainability of biomass gasification is via technological advancement and the minimization of socio-environmental effects. This paper sheds light on diverse areas of biomass gasification as a potentially sustainable and environmentally friendly technology.