Production Of Liquid Fuels Research Articles

A Novel Energy-Efficient Process for Production of Nitrogen from Air via a Reaction-Driven Membrane Reactor

Gaseous nitrogen has a wide variety of applications in industry. Currently, nitrogen is produced by energy-intensive cryogenic fractional distillation of liquefied air, pressure swing adsorption (PSA), and membranes. In this paper, a novel process was proposed and experimentally verified for production of nitrogen. In this process, oxygen in air is extracted through a dense oxygen–permeable membrane, which is then reacted with methane. By optimizing the air and methane flow rate, the process can produce nearly pure nitrogen as well as a syngas (a mixture of CO and H2). At 800 °C, the reactor produced nitrogen at a rate of 9.2 mL cm–2·min–1 with purity over 99%, and methane was reformed to syngas with CH4 throughput conversion over 90%, H2 selectivity of 92%, and CO selectivity of 92%. The syngas can be burned to generate heat or used as intermediate chemicals for production of liquid fuels and hydrogen. Since the membrane reactor is driven by the energy released by the reaction and does not consume high g...

A Co3O4-CDots-C3N4 three component electrocatalyst design concept for efficient and tunable CO2 reduction to syngas

Syngas, a CO and H2 mixture mostly generated from non-renewable fossil fuels, is an essential feedstock for production of liquid fuels. Electrochemical reduction of CO2 and H+/H2O is an alternative renewable route to produce syngas. Here we introduce the concept of coupling a hydrogen evolution reaction (HER) catalyst with a CDots/C3N4 composite (a CO2 reduction catalyst) to achieve a cheap, stable, selective and efficient route for tunable syngas production. Co3O4, MoS2, Au and Pt serve as the HER component. The Co3O4-CDots-C3N4 electrocatalyst is found to be the most efficient among the combinations studied. The H2/CO ratio of the produced syngas is tunable from 0.07:1 to 4:1 by controlling the potential. This catalyst is highly stable for syngas generation (over 100 h) with no other products besides CO and H2. Insight into the mechanisms balancing between CO2 reduction and H2 evolution when applying the HER-CDots-C3N4 catalyst concept is provided.

Techno-economic assessment of bio-oil aqueous phase-to-liquids via Fischer-Tropsch synthesis and based on supercritical water reforming

High energy demand along with large capital costs have been the main drawbacks of Fischer-Tropsch plants, which may call into question the economic viability of the Fischer-Tropsch process. The second issue is the focus of this paper, which presents a techno-economic assessment of biofuels production by a low-temperature Fischer-Tropsch synthesis with electricity as a co-product from supercritical water reforming of the bio-oil aqueous phase. A plant size of 60 t/h was considered and a heat-integrated process was designed to be energy self-sufficient, which includes syngas production and upgrading, as well as liquid fuels production by Fischer-Tropsch synthesis and refining. The simulation and optimization was performed with the aid of Aspen Plus, and some case-studies were performed. Using a feeding concentration of 25 wt%, 2.74 t/h biofuels and 5.72 MWe were obtained. In this case, by performing a discounted cash flow analysis, with 10% rate of return and 100% equity financing, the minimum selling prices for the refined FT-gasoline, FT-diesel and FT-jet fuel were 1.20, 0.93 and 0.26 €/kg (0.84, 0.75 and 0.20 €/L), respectively, which are competitive prices with respect to the market values of the equivalent fossil fuels. Likewise, the decrease in the selling prices as the plant capacity increases was also analyzed.

Conceptual design and exergy analysis of an integrated structure of natural gas liquefaction and production of liquid fuels from natural gas using Fischer-Tropsch synthesis

In this paper, utilizing absorption refrigeration system as an alternative to compression refrigeration system of MFC refrigeration cycle in an integrated superstructure with the main aim of reduction in required energy is investigated. High-energy consumption in such units is reduced because of the removal of a stage of the compression system, while the possibility of using waste energy through employing of absorption refrigeration system can be provided. A superstructure including cogeneration of heating, cooling and power for LNG production and liquid fuels using Fischer-Tropsch synthesis are investigated.Exergy analysis shows that the greatest amount of exergy destruction of equipment is related to the compressors by 28.99% and the lowest exergy destruction is related to the gas turbine by 0.17%. Integrated structure has overall thermal efficiency of 90% and specific power of 0.1988 kW h/(kg LNG)−1.

Modeling residence-time distribution in horizontal screw hydrolysis reactors

The dilute-acid thermochemical hydrolysis step used in the production of liquid fuels from lignocellulosic biomass requires precise residence-time control to achieve high monomeric sugar yields. Difficulty has been encountered reproducing residence times and yields when small batch reaction conditions are scaled up to larger pilot-scale horizontal auger-tube type continuous reactors. A commonly used naive model estimated residence times of 6.2–16.7 min, but measured mean times were actually 1.4–2.2× the estimates. This study investigated how reactor residence-time distribution (RTD) is affected by reactor characteristics and operational conditions, and developed a method to accurately predict the RTD based on key parameters. Screw speed, reactor physical dimensions, throughput rate, and process material density were identified as major factors affecting both the mean and standard deviation of RTDs. The general shape of RTDs was consistent with a constant value determined for skewness. The Péclet number quantified reactor plug-flow performance, which ranged between 20 and 357.

State-of-the - art technologies of oil shale thermal processing

Development of advanced oil shale processing technologies for production of liquid and gaseous fuels, as well as chemical raw materials, is a very topical problem. The article provides information on commercially implemented oil shale thermal processing technologies which use gaseous (Fushun, Kiviter and Petrosix) and solid (Lurgi-Ruhrgas, Tosco II, Aostra-Tasiyuk, Galoter) heat carriers. The authors note that the Galoter process implemented in plants with solid heat carriers has significant advantages compared to other processes.

Conversion of syngas to liquid hydrocarbons via a sorption-enhanced dual bed reactor

ABSTRACTFischer–Tropsch synthesis (FTS) plays an important role in the production of clean liquid transportation fuels, chemicals, and other hydrocarbon products. This study proposes a novel dual bed configuration of FTS reactor in which Zeolite 4A, with the composition of Na12 (Si12Al12O48)⋅27H2O, is considered as water adsorbent inside the first reactor. In the second converter, the heat of reaction is used to pre-heat the synthesis gas to the first bed. The simulation results show an enhancement in the gasoline production, a main decrease in undesirable product formation (CO2 and CH4), and a favorable temperature profile along the proposed concept rather than the conventional reactor. This paper shows how the concept of in-situ water adsorption is feasible and beneficial for dual bed FTS.

Carbon Chain Length Increase Reactions of Platform Molecules Derived from C5 and C6 Sugars

The production of liquid fuels from lignocellulose-derived platform molecules has attracted much interest in recent years. Platform molecules mostly have a shorter carbon chain length, compared to liquid fuels, which have a typical chain length varying between 4 and 25 carbon atoms, whereas aviation and especially diesel fuel have a carbon chain length exceeding 10 carbon atoms. For this reason, some carbon chain length increase reactions are required. In this article, carbon chain length increase reactions are compared for typical lignocellulose-derived platform molecules. The focus is placed on the ability of the molecules to participate in self-condensation reactions in a controlled manner. Hydrogen plays a key role when producing fuels from platform molecules. Hydrotreatment is applied not only when converting the products from a carbon chain length increase reaction into hydrocarbons but also for modifying the functional groups of the model compounds and, thereby, their reactivity.

Extending the basic function of lattice oxygen in lepidocrocite titanate – The conversion of intercalated fatty acid to liquid hydrocarbon fuels

We report herein the basicity of the external and internal lattice oxygen (OL) in lepidocrocite titanates with respect to CO2 and palmitic acid, respectively. Several compositions have been tested with different types of the metal M aliovalently (co)substituted for Ti, K0.8[MyTi2−y]O4 (M = Li, Mg, Fe, Co, Ni, Cu, Zn, Cu/Ni and Cu/Zn). The low CO2 desorption peak temperature (70–100°C) suggests that the external OL sites are weakly basic similar to TiO2. However, the internal OL sites are sufficiently basic to deprotonate palmitic acid, forming the intercalated potassium palmitate at the interlayer spaces. The latter serves as a two-dimensional (2D) molecular reactor for the production of liquid hydrocarbon fuels via deoxygenation under atmospheric N2. A relationship has been observed between the yield of the liquid products vs the partial charge of the lattice oxygen (δO). Since the deoxygenation pathway is highly dependent on the metal substitution, the redox-active sites might also play some roles. The co-substituted K0.8[Cu0.2Ni0.2]Ti1.6O4 produced ~68.0% yield of the liquid products, with ~ 51% saturated and ~ 15% unsaturated C15 hydrocarbons at 350°C.

(Invited) Reflections on Rust: Iron Oxide Photoelectrodes for Solar Energy Conversion and Storage

Solar water splitting is a promising route for sustainable and scalable hydrogen production from renewable sources: water and sunlight. The hydrogen can be used as a clean fuel for refueling fuel cell electric vehicles with zero emissions. Hydrogen can also serve as a feedstock for the production of drop-in liquid fuels by CO2 hydrogenation, and ammonia via the Haber–Bosch process. The greatest challenges towards viable solar water splitting technology lay in the selection and design of photocatalytic materials and devices that harvest sunlight and split water efficiently and produce hydrogen at a competitive cost. To this end photocatalytic materials that are stable in alkaline or acidic aqueous solutions, absorb visible light, promote water oxidation or reduction reactions and comprise of abundant materials must be employed. Iron oxide (α-Fe2O3, hematite), aka rust, is one of few materials meeting these criteria, but its poor transport properties and fast charge recombination present challenges for efficient charge carrier generation, separation and collection. We explore innovative solutions to these challenges using ultrathin (20-30 nm) films on specular back reflectors. This simple optical cavity design effectively traps the light in otherwise nearly translucent ultrathin films, amplifying the intensity close to the surface wherein photogenerated charge carriers can reach the surface and split water before recombination takes place. This is the enabling key towards the development of high-efficiency iron oxide photoelectrodes whose structure and properties can be tailored by design. However, the design rules for these devices remain elusive because iron oxide behaves differently than conventional semiconductors such as silicon, probably due to the strong correlation between the electrons that give rise to the current and the ions that form the crystalline lattice. Our first goal is to discover the physico-chemical processes that limit the performance of iron oxide photoelectrode and devise design principles that enable overcoming these limitations through material design at the nanoscale that combines iron oxide together with selective underlayers and overlayers that separate positive and negative charge carriers, thereby reducing recombination losses and increasing efficiency. The second goal is to apply these design principles to construct high-efficiency solar water splitting devices. The third and final goal is to invent new device architectures and operation schemes that enable affordable solar hydrogen production in large-scale applications, closing the gap between basic research on lab-scale devices and a new solar energy technology that provides stable power on demand. Figure 1

Efficient Oligomerization of Pentene into Liquid Fuels on Nanocrystalline Beta Zeolites

Light alkenes oligomerization, performed in the presence of heterogeneous acid catalysts, is an interesting alternative for the production of clean liquid fuels. The process, when catalyzed by zeolites, is flexible and can be directed to the formation of oligomers in the gasoline, jet fuel, or diesel range by adjusting the reaction conditions and the zeolite’s structure. Herein we show how reducing the crystal size of large-pore Beta zeolites down to 10–15 nm and controlling the number and strength distribution of their Bronsted acid sites leads to highly active and stable catalysts, selective to true oligomers within the naphtha and, especially, the diesel range. The shorter diffusion path lengths in the smaller crystallites and the reduced Bronsted acid site density of the two nanosized beta zeolites (10–15 nm) synthesized with Si/Al = 15 lead to 1-pentene conversion above 80% during the 6 h time on stream (TOS) at a space time (W/F) of 2.8 g·h·mol–1. This value is higher than the olefin conversion obta...

Excellent waste biomass-degrading performance of Trichoderma asperellum T-1 during submerged fermentation

The random disposal and incineration of agricultural residues cause resources waste and environmental pollution. The potential of waste biomass for the production of alternative liquid fuels is increasing and the bioconversion of lignocellulose to fermentable monomeric sugars is essential for second-generation biofuel production. Here, natural and pretreated switch grass or rice straw were fermented by both Trichoderma asperellum T-1 and Trichoderma reesei QM6a, with the fermentation results highlighted the potential of T. asperellum T-1 in the degradation of natural waste lignocellulosic materials. In fermenting different substrates, the filter paper activity, β-glucosidase activity, xylanase activity and carboxymethyl cellulase activity of T-1 can respectively reach 1.88, 8.00, 7.15 and 20.52 times that of QM6a. Although acid pretreatment could improve the enzyme activities of both T-1 and QM6a, its effect on T-1 was much smaller than that on QM6a. Moreover, strain T-1 fermented the natural rice straw better than the pretreated rice straw. Therefore, T-1 is considered to be more suitable for the degradation of natural biomass, especially for the degradation of rice straw. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscopy (SEM) showed that the cellulase series secreted by T. asperellum T-1 was more abundant, and its substrate deconstruction ability was stronger than T. reesei QM6a. All these results suggest the potential of T. asperellum T-1 in the degradation of natural waste lignocellulosic material, with practical benefits in terms of cost and pollution reduction.

Iron-Doped BaMnO3 for Hybrid Water Splitting and Syngas Generation.

A rationalized strategy to optimize transition-metal-oxide-based redox catalysts for water splitting and syngas generation through a hybrid solar-redox process is proposed and validated. Monometallic transition metal oxides do not possess desirable properties for water splitting; however, density functional theory calculations indicate that the redox properties of perovskite-structured BaMnx Fe1-x O3-δ can be varied by changing the B-site cation compositions. Specifically, BaMn0.5 Fe0.5 O3-δ is projected to be suitable for the hybrid solar-redox process. Experimental studies confirm such predictions, demonstrating 90 % steam-to-hydrogen conversion in water splitting and over 90 % syngas yield in the methane partial-oxidation step after repeated redox cycles. Compared to state-of-the-art solar-thermal water-splitting catalysts, the rationally designed redox catalyst reported is capable of splitting water at a significantly lower temperature and with ten-fold increase in steam-to-hydrogen conversion. Process simulations indicate the potential to operate the hybrid solar-redox process at a higher efficiency than state-of-the-art hydrogen and liquid-fuel production processes with 70 % lower CO2 emissions for hydrogen production.

Optimization of transformation and regeneration of Polish apple cultivar (Malus domestica cv. Alwa)

Fischer–Tropsch synthesis (FTS) is a key technology for the production of liquid fuels from syngas. Enhanced liquid fuel production and catalytic stability can be achieved by rational design of catalysts Due to the metal–promoter interaction, conventional Mn-modified ion-based catalysts showed high C2 through C4 olefin selectivity and low activity. In this paper, Mn-containing SiO2-encapsulated ion-based double-shell spindles were fabricated and employed as a FTS catalyst. For the proposed design, the SiO2 shell not only is employed as an interlayer to weaken the contact between Fe and the Mn promoter, but also acted as the anchoring site for Mn nanoparticles. The results showed that the Mn-modified FeSiMn catalyst presents higher catalytic activity (3.41 × 10−5 molCO gFe−1 s−1) and superior C5+ production (20.8 × 10−4 gHC gFe−1 s−1) compared to the unmodified FeSi catalyst. This can be ascribed to the Mn-improved spillover effect. Thus, design of double-shell catalysts provides important clues for understanding the sole effect of the promoter on catalytic performance and for improving the production of liquid fuels.

Life-cycle assessment of alternative liquid fuels production in China

Alternative liquid fuels are attracting a lot of attention due to their potential for addressing possible future oil supply shortages. In China, oil shale, coal and biomass are considered as three significant feedstocks for alternative fuels. However, quantitative assessment of the sustainability of liquid fuels production based on these feedstocks is scarce. This paper uses the LCA (life cycle assessment) method to analyze energy consumption, GHG (greenhouse gas) emissions, cost and local employment effects of liquid fuels production from these feedstocks. The results show that the energy consumption of BTL (biomass-to-liquid) processes is much lower than that of production of petroleum based fuels, whereas STL (shale-to-liquid) and CTL (coal-to-liquid) processes have higher energy consumption; the GHG emissions of BTL are much lower than those of STL and CTL, which do not perform well from a GHG emissions perspective; when the crude oil price is lower than 50 $/bbl, there is no economic advantage from the three alternative fuels studied, however the economic benefits increase with increase in the crude oil price and become clear as the crude oil price approaches 100 $/bbl. It is further found that more local job opportunities could be created by developing these three alternatives. Several policy suggestions for sustainable development of the liquid fuels industry are formulated on the basis of four assessment metrics.

Flash Pyrolysis of Oleaginous Biomass in a Fluidized-Bed Reactor

In this study, flash pyrolysis was performed using milled soybean as a model substrate to assess the production of liquid fuels from oleaginous biomass feedstocks. A laboratory-scale fluidized-bed flash pyrolysis reactor that allowed rapid heat transfer to the biomass along with short vapor residence time was designed and constructed. Pyrolysis was performed between 250 and 610 °C with a vapor residence time between 0.2 and 0.3 s. At 550 °C or higher, nearly 70% of the initial feed mass as well as feed carbon was recovered in bio-oil. In addition, 90% of the feedstock lipids were recovered in the bio-oil at these pyrolysis conditions. The high liquid products yields were attributed to (1) the low secondary degradation of bio-oils due to the short vapor residence time and (2) the high recovery of liquids in a novel dry ice packed-bed condenser that provided a high surface area for condensation/aggregation of dilute bio-oil vapors/aerosols that were entrained in the carrier gas. The bio-oil from this study had higher C and H content, higher calorific value, and lower oxygen and water content than bio-oil from wood. These results show that high-quality bio-oil at high yield can be obtained from flash pyrolysis of oleaginous feedstock.

Process Analysis for the Production of Hydrogen and Liquid Fuels from Oil Shale

AbstractShale to liquid (STL) and syngas to liquid (GTL) fuel techniques are applied to vast discovered resources of oil shale to fulfil current and future liquid fuel demands. To utilize the different constituents of oil shale efficiently, cases 1 and 2 were designed to produce liquid fuels and hydrogen as end products. In case 1, which produces shale oil and retorting gas from oil shale that are further processed by shale oil hydrogenation and retorting gas steam reforming to produce liquid fuels and hydrogen, respectively. For comparison, case 2, including oil‐shale retorting, retorting gas steam reforming, shale oil hydrogenation, and Fischer–Tropsch synthesis technology, was also established. Cases 1 and 2 are compared (with respect to end products and energy efficiencies) with each other by modeling and simulating three scenarios for case 1 and four scenarios for case 2. The simulation results show that the third scenario of case 1 and the fourth scenario of case 2 provide the most important required end products, namely, hydrogen and hydrocarbon fuels. The overall production of hydrocarbon fuels in the fourth scenario of case 2 increases 0.95 wt % more than that of the third scenario of case 1, whereas the production of hydrogen reduces by 14.7 wt % and the external energy consumption is 20 % higher in the fourth scenario of case 2, relative to that of the third scenario of case 1. For the third scenario of case 1 and fourth scenario of case 2, the total energy efficiency of the system is 43.45 % (high heating value (HHV)) and 43.16 % (HHV), respectively. The whole system is modeled and simulated in the Aspen Plus V8.4 program and the results are compatible with those of industrial and experimental data. Sensitivity analyses are performed to show the effects of various key operating parameters on the production yield of shale oil, retorting gas, and hydrogen.

Assessment of bioenergy production from mid-rotation thinning of hardwood plantation: life cycle assessment and cost analysis

Forestry thinning logs, a low-value by-product of the forestry industry, present an opportunity for bioenergy production. It can be converted into solid, liquid, and gaseous fuels via different conversion techniques. Comparative life cycle assessment and life cycle costing (LCC) analysis were conducted to evaluate six options: woodchip gasification for power generation; wood pellets gasification in combined heat and power plant; wood pellet combustion for domestic water and space heating; pyrolysis for power generation; pyrolysis with bio-oil upgrading to transportation fuels; and ethanol production for transportation fuel mix. The functional unit used in this study was the treatment of 1 Mg of biomass. Global warming; acidification; eutrophication; fossil depletion, human toxicity; and land use impact categories were considered. The LCC also included greenhouse gas (GHG) emissions costs. The effects of uncertainties in the system on the overall performance of the scenarios were also evaluated. The results showed that all options except for ethanol production are GHG emission negative. Woodchips gasification performed best in all environmental impact categories and had the lowest LCC ($177.6/Mg). Biomass drying consumed more than 50% of the energy requirement for all options except for production of liquid transportation fuels via upgrading of pyrolytic oil, in which case the fuel upgrading process was the most energy intensive. In terms of energy return, all options, except electricity production through pyrolysis, offered positive return. The results highlight the importance of using biomass with least possible processing in order to maximise environmental and energy return and minimise LCC.

Extremum Seeking Control of Carbon Monoxide Concentration in Underground Coal Gasification

Coal gasification is a promising option for the future use of coal. Similarly to gasification in industrial reactors, underground coal gasification (UCG) produces syngas, which can be used for power generation or for the production of liquid hydrocarbon fuels and other valuable chemical products. As compared with conventional mining and surface gasification, UCG promises lower capital operating costs and also has other advantages, such as no human labour underground. The main goal of the study presented in the paper was to experimentally demonstrate the structure of optimal control system of lignite underground gasification which consists from stabilization and optimization level. This paper proposes an alternative extremum seeking control design technique for the solution of real-time optimization control problems in UCG by aim to maximize a content CO in syngas.

Life cycle water demand coefficients for crude oil production from five North American locations

The production of liquid fuels from crude oil requires water. There has been limited focus on the assessment of life cycle water demand footprints for crude oil production and refining. The overall aim of this paper is address this gap. The objective of this research is to develop water demand coefficients over the life cycle of fuels produced from crude oil pathways. Five crude oil fields were selected in the three North American countries to reflect the impact of different spatial locations and technologies on water demand. These include the Alaska North Slope, California's Kern County heavy oil, and Mars in the U.S.; Maya in Mexico; and Bow River heavy oil in Alberta, Canada. A boundary for an assessment of the life cycle water footprint was set to cover the unit operations related to exploration, drilling, extraction, and refining. The recovery technology used to extract crude oil is one of the key determining factors for water demand. The amount of produced water that is re-injected to recover the oil is essential in determining the amount of fresh water that will be required. During the complete life cycle of one barrel of conventional crude oil, 1.71–8.25 barrels of fresh water are consumed and 2.4–9.51 barrels of fresh water are withdrawn. The lowest coefficients are for Bow River heavy oil and the highest coefficients are for Maya crude oil. Of all the unit operations, exploration and drilling require the least fresh water (less than 0.015 barrel of water per barrel of oil produced). A sensitivity analysis was conducted and uncertainty in the estimates was determined.