Constructing the Al deficiency in Si-O(H)-Al units based on Pt/ZSM-5 for enhanced hydrocracking of polyethylene into high-quality liquid fuel

Hydrocracking catalysis is a controllable route to plastic waste upgrading. However, the mismatched acid site-driven C-C cleavage and C=C hydrogenation process on metal restrict the efficiency and selectivity in conventional metal/acid bi-functional catalyst. Herein, we introduce Al deficiency in Si-O(H)-Al structural units of Pt/zeolite socony mobil-5 (Pt/ZSM-5) through discharge driven reduction (DR) process to precisely control the ratio of metal to acid, achieving hydrocracking of low-density polyethylene (LDPE) waste at 270 °C with 87.7% conversion and liquid fuel (C5-C21) selectivity of 77.8%. Pair distribution function (PDF) and nuclear magnetic resonance (NMR) spectroscopy demonstrate the partial absent Al sites further resulting short-range local disorder Si-O(H)-Al. Upon pyridine infrared spectroscopy (Py-IR) and CO diffuse reflectance Fourier-transform infrared (CO DRIFT) analysis, the extraction of Al modulates Brønsted acid density of Pt/ZSM-5 with DR process (Pt/Z5DR), improves the interaction between Pt and ZSM-5 support, enhances the cationic of Pt. The metal-acid balance and electron-deficient Pt favor the matching speed of light olefins hydrogenation and the cracking of macromolecule intermediates. Moreover, density functional theory (DFT) calculations identify the thermodynamic stability of Pt/Z5DR and moderate adsorption capability towards light olefins. This work confirms the great potential of precisely controlled molar of metal to acid in metal/zeolite catalysts for LDPE upcycling, providing a viable path for dealing with PE plastic wastes.

Pyrolysis of rice husk and sawdust for liquid fuel

The paper is focused on studying how to convert rice husk and sawdust into liquid fuel. Rice husk, sawdust and their mixture were pyrolyzed at the temperature between 420℃ and 540℃, and the main product of liquid fuel was obtained. The experimental result showed that the yield of liquid fuel heavily depended on the kind of feedstock and pyrolysis temperature. In the experiments, the maximum liquid yields for rice husk, sawdust and their mixture were 56% at 465 ℃, 61% at 490℃ and 60% at 475℃ respectively. Analysis with GC-MS and other apparatus indicated that the liquid fuel is a complicated organic compound with low caloric value and can be directly used as fuel oil without any up-grading. As a crude oil, the liquid fuel can be refined to be vehicle oil.

Radiation dose distribution of liquid fueled thorium molten salt reactor

A liquid fueled thorium molten salt reactor(TMSR-LF),one of the Generation IV reactors,was designed by the Shanghai Institute of Applied Physics,Chinese Academy of Sciences.This study uses the‘rt code to calculate the neutron and gamma dose rate distributions around the reactor.Multiple types of tallies and variance reduction techniques were employed to reduce calculation time and obtain convergent calculation results.Based on the calculation and analysis results,the TMSR-LF1 radiation shield with a 60-cm serpentine concrete layer and a 120-cm ordinary concrete layer is able to meet radiation requirements.The gamma dose rate outside the reactor biological shield was 16.1 mSv h-1;this is higher than the neutron dose rate of 3.71×10^(–2)mSv h^(-1).The maximum thermal neutron flux density outside the reactor biological shield was 1.899103 cm^(-2)s^(-1),which was below the 19105 cm^(-2)s^(-1)limit.

Atomically dispersed catalysts for small molecule electrooxidation in direct liquid fuel cells

Direct liquid fuel cells(DLFCs) have received increasing attention because of their high energy densities,instant recharging abilities, simple cell structure, and facile storage and transport. The main challenge for the commercialization of DLFCs is the high loading requirement of platinum group metals(PGMs) as catalysts. Atomically dispersed catalysts(ADCs) have been brought into recent focus for DLFCs due to their well-defined active sites, high selectivity, maximal atom-utilization, and anti-poisoning property. In this review, we summarized the structure–property relationship for unveiling the underlying mechanisms of ADCs for DLFCs. More specifically, different types of fuels used in DLFCs such as methanol, formic acid,and ethanol were discussed. At last, we highlighted current challenges, research directions, and future outlooks towards the practical application of DLFCs.

Dealuminated ZSM-5 Zeolite Catalyst for Ethylene Oligomerization to Liquid Fuels

Ethylene oligomerization using ZSM-5 zeolite was investigated to study the role of Bronsted acid sites in the formation of higher hydrocarbons. The oligomerization of olefins, dependent on the acidity of ZSM-5 zeolite, is an important step in the conversion of natural gas to liquid fuels. The framework Si/Al ratio reflects the number of potential acid sites and the acid strength of the ZSM-5 catalyst. ZSM-5 with the mole ratio SiO2/Al2O3 equal to 30 was dealuminated for different periods of time according to the acidic ion-exchange method to produce ZSM-5 with various Si/Al ratios. The FT-IR analysis revealed that the integrated framework aluminum band, non-framework aluminum band, and silanol groups areas of the ZSM-5 zeolites decreased after being dealuminated. The performance of the dealuminated zeolite was tested for ethylene oligomerization. The results demonstrated that the dealumination of ZSM-5 led to higher ethylene conversion, but the gasoline selectivity was reduced compared to the performance of a ZSM-5 zeolite. The characterization results revealed the amount of aluminum in the zeolitic framework, the crystallinity of the ZSM-5 zeolite, and the Si/Al ratio affected the formation of Bronsted acid sites. The number of the Bronsted acid sites on the catalyst active sites is important in the olefin conversion to liquid hydrocarbons.

A Direct Liquid Fuel Cell with High Power Density Using Reduced Phosphotungstic Acid as Redox Fuel

Direct liquid fuel cells(DLFCs)are proposed to address the problems of high cost and complex storage and transportation of hydrogen in traditional hydrogen-oxygen proton exchange membrane fuel cells.However,present fuels of organic small molecules used in DLFCs are restricted to problems of sluggish electrochemical kinetics and easily poisoning of precious metal catalysts.Herein,we demonstrate reduced phosphotungstic acid as a liquid fuel for DLFCs based on its advantages of high chemical and electrochemical stability,high electrochemical activity on common carbon material electrodes,and low permeability through proton exchange membranes.The application of phosphotungstic acid fuel effectively solves the problems of high cost of anode catalysts and serious fuel permeation loss in traditional DLFCs.A phosphotungstic acid fuel cell achieves a peak power density of466 mW cm^(-2)at a cell voltage of 0.42 V and good stability at current densities in the range from 20 to 200 mA cm^(-2).

Stepwise Pyrolysis by LBCR Downstream to Enhance of Gasoline Fraction of Liquid Fuel from MMSW

Pyrolysis is one of the thermal cracking methods to convert hydrocarbon to liquid fuel.The quantity and quality of the process are dependent on several condition including temperature,reaction time,catalyst,and the type of reactor.Meanwhile,a gasoline fraction was maximum product to be considered in the pyrolisis process.Therefore,this study aims to increase the gasoline fraction in liquid fuel using stepwise pyrolysis with a long bed catalytic reactor downstream(LBCR).The LBCR downstream was equipped with the top and bottom outlet and the fed source was mixed municipal solid waste(MMSW).The activated natural dolomite at 500℃ was used to allow the repetition of the secondary cracking.Also,the reactor temperature was setup at around 200℃-300℃ and the pyrolizer was 400℃.To analyze the gasoline fraction and physical properties of liquid fuel,Gas Chromatography-Mass Spectroscopy(GC-MS)and ASTM standard were employed.The experimental results showed there was a significant increase in the gasoline fraction of liquid fuels compared to using direct catalytic cracking and absence of catalysts.By using a LBCR at 250℃,the liquid fuel obtained at top outlet(TO)and bottom outlet(BO)have 84.08 and 56.94 percent peak area of gasoline fraction(C5-C12),respectively.The average value(TO and BO)of the fraction at 250℃ by LBCR was 70.51 percent peak area and it was increased by about 93.6%and 51.14%compared to without catalyst and direct catalytic,respectively.Furthermore,pyrolytic liquid oils were found to have kinematic viscosity of 2.979 and 0.789 cSt,density of 0.781 and 0.782 g/cm^(3),and flash point<−5℃ for BO-250 and TO-250 liquid fuel,respectively.These results showed BO liquid fuel was comparable to diesel conventional fuel while TO liquid fuel was comparable to gasoline.Evidently,the presence of LBCR made a major contribution to generate multi secondary cracking and to produce more gasoline fraction from mixed MMSW feedstock,as well as to increase the physical properties of liquid fuel.

Techno-Economic Evaluation of Thermal and Catalytic Pyrolysis Plants for the Conversion of Heterogeneous Waste Plastics to Liquid Fuels in Nigeria

Techno-economic potentials of thermal and catalytic pyrolysis plants for the conversion of waste plastics to liquid fuels have been widely studied, but it is not obvious which of the two plants is more profitable, as the existing studies used different assumptions and cost bases in their analyses, thereby making it difficult to compare the economic potentials of the two plants. In this study, industrial-scale thermal and catalytic waste plastics pyrolysis plants were designed and economically analyzed using ASPEN PLUS. Amorphous silica-alumina was considered the optimum catalyst, with 3:1 feed to catalyst ratio. Based on 20,000 tons/year of feed and 20% interest rate, the catalytic plant, having a net present value (NPV) of &#83582208 million, was found to be economically less attractive than the thermal plant, having the NPV of &#83582426.4 million. On the contrary, sensitivity analyses of the two plants at a feed rate of 50,000 tons/year gave rise to a slightly higher NPV for the catalytic plant (&#83589861 million) than the thermal plant having NPV of &#83589838 million, thereby making the former more economically attractive for processing large amounts of waste plastics into liquid fuels. Consequently, as the catalytic plant showed a better scale economy and would produce higher quality liquid fuels than the thermal plant, it is recommended for commercialization in Nigeria.

Transforming liquid flow fuel cells to controllable reactors for highlyefficient oxidation of 5-hydroxymethylfurfural to 2, 5-furandicarboxylic acid at low temperature

Highly-efficient oxidation of 5-hydroxymethylfurtural(HMF) to 2,5-furandicarboxylic acid(FDCA) at low temperature with air as the oxidant is still challenging.Herein,inspired by the respirato ry electron transport chain(ETC) of living cells mediated by electron carriers,we constructed artificial ETCs and transformed liquid flow fuel cells(LFFCs) to flexible reactors for efficient oxidation of HMF to produce FDCA under mild conditions.This LFFC reactor employed an electrodeposition modified nickel foam as an anode to promote HMF oxidation and(VO_(2))_(2)SO_(4) as a cathode electron carrier to facilitate the electron transfer to air.The reaction rate could be easily controlled by selecting the anode catalyst,adjusting the external loading and changing the cathodic electron carrier or oxidants.A maximal power density of 44.9 mW cm^(-2) at room temperature was achieved,while for FDCA production,short-circuit condition was preferred to achieve quick transfer of electrons.For a single batch operation with 0.1 M initial HMF,FDCA yield reached 97.1%.By fed-batch operation,FDCA concentration reached 144.5 g L^(-1) with a total yield of 96%.Ni^(2+)/Ni^(3+) redox couple was the active species mediating the electron transfer,while both experimental and DFT calculation results indicated that HMFCA pathway was the preferred reaction mechanism.

Mathematical modeling of fuel cells fed with an electrically rechargeable liquid fuel

Lately,utilizing a novel electrically rechargeable liquid fuel(e-fuel),a fuel cell has been designed and fabricated,which is demonstrated to achieve a much better performance than alcoholic liquid fuel cells do.However,its current performance,which thus hampers its wide application,demands further improvement to meet up with industrial requirement.Therefore,to attain a better performance for this system,an in-depth understanding of the complex physical and chemical processes within this fuel cell is essential.To this end,in this work,a two-dimensional transient model has been developed to gain an extensive knowledge of a passive e-fuel cell and analyze the major factors limiting its performance.The effects of various structural parameters and operating conditions are studied to identify the underlying performance-limiting factors,where deficient mass transport is found to be one of the major causes.The increment of anode porosity and thickness are found to be effective methods of improving the cell performance.This study therefore provides insights on achieving further per-formance advancement of the fuel cell in the future.

Analysis of technology pathway of China's liquid fuel production with consideration of energy supply security and carbon price

Efforts to provide alternative resources and technologies for producing liquid fuel have recently been intensified.Different levels of dependence on oil imports and carbon prices have a significant impact on the composition of the cost-minimizing portfolio of technologies.Considering such factors,how should China plan its future liquid fuel industry?The model for supporting the technology portfolio and capacity configuration that minimizes the total system cost until 2045 is described in this study.The results obtained for different carbon prices and levels of dependence on oil import indicate that the oil-to-liquid fuel(OTL)will remain dominant in China's liquid fuel industry over the next three decades.If the carbon price is low,the coal-to-liquid fuel(CTL)process is competitive.For a high carbon price,the biomass-to-liquid fuel(BTL)technology expands more rapidly.The results also reveal that developing the BTL and CTL can effectively reduce the oil-import dependency;moreover,a high carbon price can lead to the CTL being replaced with the low-carbon technology(e.g.,BTL).Improvement in energy raw material conversion and application of CO_(2) removal technologies are also effective methods to control carbon emissions for achieving the carbon emission goals and ultimately emission reduction targets.

Modified electronic structure and enhanced hydroxyl adsorption make quaternary Pt-based nanosheets efficient anode electrocatalysts for formic acid-/alcohol-air fuel cells

Surface/interface engineering of a multimetallic nanostructure with diverse electrocatalytic properties for direct liquid fuel cells is desirable yet challenging.Herein,using visible light,a class of quaternary Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)ultrathin nanosheets is fabricated and used as high-performance anode electrocatalysts for formic acid-/alcohol-air fuel cells.The modified electronic structure of Pt,enhanced hydroxyl adsorption,and abundant exterior defects afford Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C high intrinsic anodic electrocatalytic activity to boost the power densities of direct formic acid-/methanol-/ethanol-/ethylene glycol-/glycerol-air fuel cells,and the corresponding peak power density of Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C is respectively 129.7,142.3,105.4,124.3,and 128.0 mW cm^(-2),considerably outperforming Pt/C.Operando in situ Fourier transform infrared reflection spectroscopy reveals that formic acid oxidation on Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)/C occurs via a CO_(2)-free direct pathway.Density functional theory calculations show that the presence of Ag,Bi,and Te in Pt_(1)Ag_(0.1)Bi_(0.16)Te_(0.29)suppresses CO^(*)formation while optimizing dehydrogenation steps and synergistic effect and modified Pt effectively enhance H_(2)O dissociation to improve electrocatalytic performance.This synthesis strategy can be extended to 43 other types of ultrathin multimetallic nanosheets(from ternary to octonary nanosheets),and efficiently capture precious metals(i.e.,Pd,Pt,Rh,Ru,Au,and Ag)from different water sources.

Development of high intensity low emission combustor for achieving flameless combustion ofliquid fuels

This paper presents the experimental and numerical results for a two stagecombustor capable of achieving flameless combustion with liquid fuels for different thermalheat inputs of 20,30,40 and 60 kW and heat release density of 5-15 MW/m^(3).Combustioncharacteristics and pollutant emissions are studied for three different fuels,kerosene,diesel andgasoline.The influence of droplet diameter on pollutant emissions at all conditions is studied.The fuel and oxidizer are supplied at ambient conditions.The concept of high swirl flows hasbeen adopted to achieve high intemal recirculation rates,residence time and increased dilutionof the fresh reactants in the primary combustion zone,resulting in flameless combustion mode.Air is injected through four tangential injection ports located near the bottom of the combustorand liquid fuel is injected through a centrally mounted pressure swirl injector.Computationalanalysis of the flow features shows that decrease in the exit port diameter of the primarychamber increases the recirculation rate of combustion products and helps in achieving theflameless combustion mode.Based on preliminary computational studies,a 30 mm primarychamber exit pont diameter is chosen for experimental studies.Detailed experimentalinvestigations show that flameless combustion mode was achieved with evenly distributedcombustion reaction zone and unifom temperature distribution in the combustor.Pollutant emissions of CO, NO_(x),C_(x)H_(y) are measured and compared for all operating conditions ofdifferent fuels and different thermal inputs. The acoustic emission levels are reduced by6-8 dB as combustion mode shifts from conventional mode to flameless combustion mode.

Review of the direct thermochemical conversion of lignocellulosic biomass for liquid fuels

Increased demand for liquid transportation fuels, environmental concerns and depletion of petroleum resources requires the development of efficient conversion technologies for production of second-generation biofuels from non-food resources. Thermochemical approaches hold great potential for conversion of lignocellulosic biomass into liquid fuels. Direct thermochemical processes convert biomass into liquid fuels in one step using heat and catalysts and have many advantages over indirect and biological processes, such as greater feedstock flexibility, integrated conversion of whole biomass, and lower operation costs. Several direct thermochemical processes are employed in the production of liquid biofuels depending on the nature of the feedstock properties: such as fast pyrolysis/liquefaction of lignocellulosic biomass for bio-oil, including upgrading methods, such as catalytic cracking and hydrogenation. Owing to the substantial amount of liquid fuels consumed by vehicular transport, converting biomass into drop-in liquid fuels may reduce the dependence of the fuel market on petroleumbased fuel products. In this review, we also summarize recent progress in technologies for large-scale equipment for direct thermochemical conversion. We focus on the technical aspects critical to commercialization of the technologies for production of liquid fuels from biomass,including feedstock type, cracking catalysts, catalytic cracking mechanisms, catalytic reactors, and biofuel properties. We also discuss future prospects for direct thermochemical conversion in biorefineries for the production of high grade biofuels.

Chemical storage of hydrogen in synthetic liquid fuels:building block for CO_(2)-neutral mobility

Green hydrogen is anticipated to play a major role in the decarbonization of the mobility sector.Its chemical storage in CO_(2)-neutral synthetic liquid fuels is advantageous in terms of safety and reliability compared to other hydrogen storage developments,and thus represents a complementary building block to developments in electric and hydrogen mobility for the low-carbon transition in the mobility sector.Its development is especially relevant for transport sectors which will have no alternatives to liquid fuels in the foreseeable future.In this paper,three alternative technological routes for the chemical storage of hydrogen in CO_(2)-neutral synthetic liquid fuels are identified and comparatively evaluated in terms of feedstock potential,product potential,demand for renewable electricity and associated costs,efficiency as well as expected market relevance.While all three routes exhibited similar levels of overall efficiencies,electricity-based liquid fuels in Germany are currently limited by the high cost and limited supply of renewable electricity.In contrast,liquid fuels generated from biogenic waste have a constant supply of biogenic feedstock and are largely independent from the supply and cost of renewable electricity.

Review on the Relationship Between Liquid Aerospace Fuel Composition and Their Physicochemical Properties

The development of advanced air transportation has raised new demands for high-performance liquid hydrocarbon fuels.However,the measurement of fuel properties is time-consuming,cost-intensive,and limited to the operating conditions.The physicochemical properties of aerospace fuels are directly infl uenced by chemical composition.Thus,a thorough investigation should be conducted on the inherent relationship between fuel properties and composition for the design and synthesis of high-grade fuels and the prediction of fuel properties in the future.This work summarized the eff ects of fuel composition and hydrocarbon molecular structure on the fuel physicochemical properties,including density,net heat of combustion(NHOC),low-temperature fl uidity(viscosity and freezing point),fl ash point,and thermal-oxidative stability.Several correlations and predictions of fuel properties from chemical composition were reviewed.Additionally,we correlated the fuel properties with hydrogen/carbon molar ratios(n H/C)and molecular weight(M).The results from the least-square method implicate that the coupling of H/C molar ratio and M is suitable for the estimation of density,NHOC,viscosity and eff ectiveness for the design,manufacture,and evaluation of aviation hydrocarbon fuels.

Development of High-Energy-Density Liquid Aerospace Fuel:A Perspective

Aerospace aircraft has significantly improved the life quality of human beings and extended the capability of space explosion since its appearance in 1903,in which liquid propellants or fuels provide the key power source.For jet fuels,its property of energy density plays an important role in determining the flight range,load,and performance of the aircraft.Therefore,the design and fabrication of high-energy-density(HED)fuels attract more and more attention from researchers all over the world.Herein,we briefly introduce the development of liquid jet fuels and HED fuels and demonstrate the future development of HED fuels.To further improve the energy density of fuel,the approaches of design and construction of multi-cyclic and stained molecule structures are proposed.To break through the density limit of hydrocarbon fuels,the addition of energetic nanoparticles in HED fuels to produce nanofluid or gelled fuels may provide a facile and effective method to significantly increase the energy density.This work provides the perspective for the development of HED fuels for advanced aircrafts.

THEORETICAL ANALYSIS OF THE BACKDRAFT PHENOMENA INDUCED BY LIQUID FUEL

A dynamical model of temperature of hot smoke layer is quantitatively established based on the whole backdraft procedure induced by liquid fuel. The whole procedure consists of the preburn fire (the first period), the secondary fuel injection (the second period) and backdraft development (the third period). The model considers enthalpy loss of liquid fuel vola- tilization and hot smoke layer mass gain. In this paper, simulative results of the model are well compared with experimental results, and simulative results of the model are analyzed. Furthermore, combustion efficiency under limited ventilation and practical combustion reaction rate are worth investigating.

Efficient and sustainable V-catalyzed oxidative desulfurization of fuels assisted by ionic liquids

Fuel desulfurization is an appealing topic for the chemical industry since severe environmental regulations regarding SO_2 emissions have been legislated in many countries. In order to reduce the amount of sulfur-containing compounds in fuels,responsible for high SO_x emission levels,a green chemistry approach is compulsory. In this paper,vanadium salen and salophen complexes were used in the oxidation of a model aromatic sulfide,such as dibenzothiophene( DBT),in the presence of H_2O_2 as green oxidant. The oxidative process was successfully coupled with the extraction of the oxidized compounds by ionic liquids. The system resulted highly selective for sulfide oxidation,showing poor reactivity toward the oxidation of alkenes and allowing a significant reduction of S content in a model benzine. To note,the use of microwave in place of standard heating allowed to obtain 98% of DBT oxidation and almost complete sulfur extraction in the model fuel in 1000 s. For these reasons,this system was considered an easy,rapid and clean process to achieve fuel desulfurization.