Nan Xu

Bio: Nan Xu is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Ignition system & Combustion. The author has an hindex of 7, co-authored 7 publications receiving 280 citations.

Review on the production methods and fundamental combustion characteristics of furan derivatives

Abstract: Furan derivatives (DMF (2,5-dimethylfuran), MF (2-methylfuran), and furan) are the attractive oxygenated fuels to reduce the consumption of fossil fuel and engine emissions due to their comparable combustion properties to those of commercial gasoline and the productivities from lignocellulosic raw materials. Many experimental studies have been focused on these promising fuel characteristics including laminar burning velocities, laminar flame structures, ignition delay times, and pyrolysis species. Various kinetic mechanisms have been developed in detail as well based on up to date experimental data in accordance with the quantum chemical calculations. In the present study, the vast amount of experimental data have been collected, consolidated, and reviewed along with the kinetic model validations in order to envision a future fuel research on furan derivatives for minimizing the experimental uncertainties, improving the data fidelity, and developing accurate kinetic models.

Thermal and Chemical Effects of Water Addition on Laminar Burning Velocity of Syngas

Abstract: An experimental and numerical study on thermal and chemical effects of water vapor addition on the laminar burning velocities of syngas was conducted using a constant-volume chamber and CHEMKIN package. The experimental conditions in the present study for CO/H2/air/H2O mixtures with hydrogen fraction in syngas were from 5% to 50%, initial temperature of 373 K, pressures of 0.1 and 0.5 MPa and water dilution ratios from 0% to 30%. The measured laminar burning velocity data were compared with simulations with three mechanisms, the San Diego mechanism and those of Davis et al. and Li et al. The experimental data showed a reasonable agreement with the calculated values at low and high pressures when the content of H2 in the fuel was low. However, when H2/CO ratio in the fuel was higher (75/25 and 95/05), all three mechanisms overpredicated the laminar burning velocity for fuel-rich mixtures. Sensitivity analysis was performed to identify the possible sources of discrepancy between the experimental data and ca...

Experimental and Kinetic Study on the Ignition Delay Times of 2,5- Dimethylfuran and the Comparison to 2‑Methylfuran and Furan

Abstract: The ignition phenomena of 2,5-dimethylfuran (DMF), 2-methylfuran (MF), and furan are systematically investigated. Ignition delay times are measured over the temperature range of 1150–2010 K and pressures of 1.2, 4, and 16 bar for lean, stoichiometric, and rich DMF/Ar/O2 mixtures. For comparison, similar measurements for stoichiometric MF/O2/Ar and furan/O2/Ar are also conducted. Through a multi-regression analysis, the measured ignition delay times of DMF are fitted empirically in an Arrhenius-like form as a function of experimental parameters. It is observed that, when the fuel concentration, pressure, temperature, and equivalence ratio are kept constant, furan has the longest ignition delay times, while the reactivity of DMF and MF strongly depends upon the temperature. The experimental ignition delay times are compared to model predictions of Somers et al. and Liu et al. Both models could give qualitative agreement with DMF and MF ignition data, while the model of Somers et al. provides better quantita...

How Catalysts and Experimental Conditions Determine the Selective Hydroconversion of Furfural and 5-Hydroxymethylfurfural.

Abstract: Furfural and 5-hydroxymethylfurfural stand out as bridges connecting biomass raw materials to the biorefinery industry. Their reductive transformations by hydroconversion are key routes toward a wide variety of chemicals and biofuels, and heterogeneous catalysis plays a central role in these reactions. The catalyst efficiency highly depends on the nature of metals, supports, and additives, on the catalyst preparation procedure, and obviously on reaction conditions to which catalyst and reactants are exposed: solvent, pressure, and temperature. The present review focuses on the roles played by the catalyst at the molecular level in the hydroconversion of furfural and 5-hydroxymethylfurfural in the gas or liquid phases, including catalytic hydrogen transfer routes and electro/photoreduction, into oxygenates or hydrocarbons (e.g., furfuryl alcohol, 2,5-bis(hydroxymethyl)furan, cyclopentanone, 1,5-pentanediol, 2-methylfuran, 2,5-dimethylfuran, furan, furfuryl ethers, etc.). The mechanism of adsorption of the ...

Advanced Biofuels and Beyond: Chemistry Solutions for Propulsion and Production.

Abstract: Sustainably produced biofuels, especially when they are derived from lignocellulosic biomass, are being discussed intensively for future ground transportation. Traditionally, research activities focus on the synthesis process, while leaving their combustion properties to be evaluated by a different community. This Review adopts an integrative view of engine combustion and fuel synthesis, focusing on chemical aspects as the common denominator. It will be demonstrated that a fundamental understanding of the combustion process can be instrumental to derive design criteria for the molecular structure of fuel candidates, which can then be targets for the analysis of synthetic pathways and the development of catalytic production routes. With such an integrative approach to fuel design, it will be possible to improve systematically the entire system, spanning biomass feedstock, conversion process, fuel, engine, and pollutants with a view to improve the carbon footprint, increase efficiency, and reduce emissions.

Efficient conversion of 5-hydroxymethylfurfural to high-value chemicals by chemo- and bio-catalysis

Abstract: 5-hydroxymethylfurfural (HMF) is a very important versatile platform compound derived from renewable biomass. The functionalized molecule with an aldehyde group, a hydroxyl group and a furan ring provides great potential for the production of a wide variety of valuable chemicals. This review highlights the latest advances in the catalytic conversion of HMF into value-added chemicals by some important reactions including (1) aerobic oxidation of HMF into furan-based aldehydes and acids such as 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), 2,5-diformylfuran (DFF), and furandicarboxylic acid (FDCA), (2) reductive amination of HMF to amine, (3) the synthesis of aromatics by Diels–alder reaction followed by a dehydration reaction, (4) catalytic reduction of HMF into 2,5-bis(hydroxymethyl)furan (BHMF), and 2,5-dimethyl furan (DMF), (5) catalytic oxidation of HMF into maleic anhydride, and some other important transformations. The review mainly focuses on the recent progress in bio-catalytic, electrocatalytic, and heterogeneous catalytic transformation of HMF into high value chemicals over the past few years. Moreover, an outlook is provided to highlight opportunities and challenges related to this hot research topic.

2-Methylfuran (MF) as a potential biofuel: A thorough review on the production pathway from biomass, combustion progress, and application in engines

Abstract: Currently, the development of alternative and green energy sources has been being strongly pushed aiming to recoup the lack of fossil energy, to meet the ever-increasing demand of energy use in modern society, and to palliate concerns regarding environmental pollution and global climate change. Therefore, producing energy from biomass sources has recently been of great interest because biomass is considered as a reliable and ubiquitous source. Indeed, the conversion of biomass into furan derivatives through the catalytic production process is emerging as a fascinating and promising method. Being one of the furan-based compounds, 2-Methylfuran (MF) is known as a critical platform substance and an ideal green solution on the pathway of finding alternative fuels because the MF properties are similar to those of fossil fuels and MF could be generated from renewable biomass source. In this review paper, the process of MF synthesis from biomass through catalyst reactions was thoroughly analyzed. More importantly, the pyrolysis and oxidation progress of MF was also critically presented aiming to clarify the applicability of MF to internal combustion engines. Finally, the performance, the characteristics of combustion, and pollutant formation of internal combustion engines fueled with MF were discussed in detail. In general, MF could become a promising alternative fuel for internal combustion engines although studies on the engine durability, compatibility to materials, tribology behaviors should be further carried out in the future.