Fuel Range Hydrocarbons Research Articles

Hydrocracking of Polyethylene to Jet Fuel Range Hydrocarbons over Bifunctional Catalysts Containing Pt- and Al-Modified MCM-48

A low-density polyethylene was hydrocracked to liquid hydrocarbons in autoclave reactors over catalysts containing Pt- and Al-modified MCM-48. Two kinds of Al-modified MCM-48 were synthesized for the reaction: Al-MCM-48 was synthesized using a sol–gel method by mixing Al(iso-OC3H7)3 with Si(OC2H5)4 and surfactant in a basic aqueous solution before hydrothermal synthesis, and Al/MCM-48 was synthesized using a post-modification method by grafting Al3+ ions on the surface of calcined Al/MCM-48. X-ray diffraction (XRD) patterns indicated that both Al-MCM-48 and Al/MCM-48 had a cubic mesoporous structure. The Brunauer–Emmett–Teller (BET) surface areas of Al-MCM-48 and Al/MCM-48 were larger than 1000 m2/g. 27Al Magic Angle Spinning-NMR (MAS NMR) indicated that Al3+ in Al-MCM-48 was located inside the framework of mesoporous silica, but Al3+ in Al/MCM-48 was located outside the framework of mesoporous silica. The results of ammonia temperature-programmed desorption (NH3-TPD) showed that the acidic strength of various samples was in the order of H-Y > Al/MCM-48 > Al-MCM-48 > MCM-48. After 4 MPa H2 was charged in the autoclave at room temperature, 1 wt % Pt/Al/MCM-48 catalyst showed a high yield of C9−C15 jet fuel range hydrocarbons of 85.9% in the hydrocracking of polyethylene at 573 K for 4 h. Compared with the reaction results of Pt/Al/MCM-48, the yield of light hydrocarbons (C1−C8) increased over Pt/H-Y, and the yield of heavy hydrocarbons (C16−C21) increased over Pt/Al-MCM-48 in the hydrocracking of polyethylene. The yield of C9−C15 jet fuel range hydrocarbons over the used catalyst did not decrease compared to the fresh catalyst in the hydrocracking of polyethylene to jet fuel range hydrocarbons over Pt/Al/MCM-48.

Pyrolysis of waste expanded polystyrene and reduction of styrene via in-situ multiphase pyrolysis of product oil for the production of fuel range hydrocarbons

Upgraded fuel oil was produced from the waste expanded polystyrene (WEPS) using pyrolysis and in-situ selective aromatization in a specially designed reactor. The catalytic pyrolysis of WEPS was performed keeping the catalyst in three different types of catalyst arrangements inside the reactor i.e., A-type/catalyst in liquid phase, B-type/catalyst in vapour phase, and AB-type or Multiphase/catalyst in both liquid and vapour phases, respectively. The ZSM-5 ammonium powder was used as a catalyst with varying feed to catalyst ratio and 20:1 was found to be optimum. Aromatics of fuel range like benzene, toluene, and ethylbenzene (BTE) were significantly increased and styrene got reduced by many folds when AB-type/multiphase catalytic pyrolysis was performed. The thermal pyrolysis produced maximum liquid yield of 94.37 wt% at a temperature of 650 °C and a heating rate of 15 °C/min. The maximum liquid yield of 88.05 wt%, 78.85 wt%, and 75.11 wt% were obtained for the A-type, B-type, and AB-type catalytic pyrolysis at the temperature of 600 °C, 550 °C and 550 °C, respectively using the same heating rate. The liquid oil of thermal pyrolysis contains very low amount of fuel range aromatics i.e., BTE of 11.38 wt% and the highest amount of styrene (84.74 wt%). In contrarily, BTE content for the catalytic process increased progressively in the order of 18.98 wt% (A-type) < 24.27 wt% (B-type) < 28.12 wt% (AB-type). The styrene content significantly decreased to a very low value of 46.30 wt% for AB-type/multiphase pyrolysis at the temperature of 550 °C.

CoMn Catalysts Derived from Hydrotalcite-Like Precursors for Direct Conversion of Syngas to Fuel Range Hydrocarbons

Two different groups of CoMn catalysts derived from hydrotalcite-like precursors were prepared through the co-precipitation method, and their performance in the direct production of gasoline and jet fuel range hydrocarbons through Fischer–Tropsch (FT) synthesis was evaluated in a batch autoclave reactor at 240 °C and 7 MPa and H2/CO of 2. The physicochemical properties of the prepared catalysts were investigated and characterized using different characterization techniques. Catalyst performance was significantly affected by the catalyst preparation method. The crystalline phase of the catalyst prepared using KOH contained Co3O4 and some Co2MnO4.5 spinels, with a lower reducibility and catalytic activity than cobalt oxide. The available cobalt active sites are responsible for the chain growth, and the accessible acid sites are responsible for the cracking and isomerization. The catalysts prepared using KOH + K2CO3 mixture as a precipitant agent exhibited a high selectivity of 51–61% for gasoline (C5–C10) and 30–50% for jet fuel (C8–C16) range hydrocarbons compared with catalysts precipitated by KOH. The CoMn-HTC-III catalyst with the highest number of available acid sites showed the highest selectivity to C5–C10 hydrocarbons, which demonstrates that a high Brønsted acidity leads to the high degree of cracking of FT products. The CO conversion did not significantly change, and it was around 35–39% for all catalysts. Owing to the poor activity in the water-gas shift reaction, CO2 formation was less than 2% in all the catalysts.

Jet Fuel Range Hydrocarbon Production from Propanal: Mechanistic Insights into Active Site Requirement of a Dual-Bed Catalyst

Utilization of sustainable biomass to produce jet fuel range hydrocarbons is imperatively needed to mitigate CO2 emissions and to liberate the over-reliance on fossil resources. Using propanal as the feedstock, an excellent jet fuel range hydrocarbon yield (81.7%), high conversion (ca. 100%), and purity (85%) were achieved over a novel dual-bed Cu/SiO2–TiO2||Ni/ZSM-5 catalyst at low temperature and pressure in only one reactor. The intrinsic active site requirement was further investigated by multitechniques including density functional theory calculation, quantitative CO2/NH3-temperature-programmed desorption/diffuse reflectance infrared Fourier-transform spectroscopy, high-resolution transmission electron microscopy, and thermogravimetric analysis–mass spectrometry. Results showed that for the upstream bed catalyst (Cu/SiO2–TiO2), the Ti–O site pair and Ti Lewis acid site were crucial for enolate formation, carbon-chain growth, and ring closure reactions, which can be altered by the calcination temperature. The synergy between the site strength and number led to a volcanic relationship between acidity/basicity and the intermediate yield. In addition, the downstream bed Ni/HZSM-5 catalyst promoted the hydrodeoxygenation reaction toward hydrocarbon formation.

Jet fuel range hydrocarbon synthesis through ethylene oligomerization over platelet Ni-AlSBA-15 catalyst

Converting ethylene to biojet fuel range hydrocarbons via oligomerization is an important step in biojet production from ethanol. The present study investigates the catalytic ethylene oligomerization over platelet Ni-AlSBA-15 mesoporous catalysts. The catalysts are synthesized and characterized using nitrogen adsorption–desorption isotherms, X-ray fluorescence and X-ray diffraction techniques. The catalytic performances are then evaluated in a continuous flow fixed-bed reactor under various conditions of reaction weight hourly space velocities (0.56–4.5 h−1), temperatures (150–350 °C) and pressures (1–20 bar). Experimental results demonstrate that platelet Ni-AlSBA-15 is a promising catalyst for the ethylene oligomerization to produce biojet fuel range hydrocarbons. It performs a good catalytic activity, yielding 98–99 mol% ethylene conversion and 34–42 wt% C8+ selectivity at 0.56 h−1, 275–300 °C and 20 bar. The obtained products contain mainly C4–C10 olefins with low aromatic compounds. Moreover, the catalyst exhibits good stability of the activity during long periods of operation.

Selective deoxygenation of fatty acids to fuel-range hydrocarbons over Pt-MOx/ZrO2 (M = Mo and W) catalysts

A comparative catalytic activity study of Pt-MoOx/ZrO2 and Pt-WOx/ZrO2 for deoxygenation of oleic acid (OA) forming fuel-range, linear hydrocarbons is reported. These catalysts (with 4 wt% Pt and 8 wt% Mo or W) were prepared by a sequential wet-impregnation method and characterized for the structural and electronic properties. Pt-MoOx/ZrO2 showed higher catalytic activity than Pt-WOx/ZrO2. Hydrodeoxygenation was the selective pathway over these bifunctional catalysts yielding n-octadecane. High conversion of OA was achieved at 200 °C itself. On the contrary, monometallic Pt/ZrO2 was weakly active. It was selective mainly toward decarboxylation/decarbonylation producing n-heptadecane. Higher amounts of Pt and metal oxide in reduced forms are responsible for the high hydrodeoxygenation activity and selectivity of these reusable, bimetallic catalysts.

Enhancing jet fuel range hydrocarbons production from catalytic co-pyrolysis of Douglas fir and low-density polyethylene over bifunctional activated carbon catalysts

Low-cost and high-efficiency catalysts are vital to the conversion of solid wastes into biofuels or chemicals. In this study, a bifunctional activated carbon catalyst modified with Fe (Fe/AC) was obtained and applied to the catalytic co-pyrolysis of Douglas fir (DF) and low-density polyethylene (LDPE) using a facile fixed bed reactor. The effects of Fe loading amount, catalyst to feedstock ratio, and pyrolysis temperature on the product yields and distributions were studied. Results showed that the highest yield of bio-oil (53.67%) was achieved using 10Fe/AC at a pyrolysis temperature of 500 °C with a catalyst to feedstock ratio of 1. The main chemical compositions of the obtained catalytic bio-oil were aromatics, alkanes, and phenols. Increasing the temperature (450–600 °C) and catalyst to feedstock ratio (0.5–2) enhanced the selectivity of aromatics at the expense of phenols and alkanes. Compared to the AC catalyst, Fe/AC exhibited excellent performance on aromatics production (especially mono-aromatics) due to the newly created acid sites. The catalytic synergistic effect over 10Fe/AC significantly promoted the formation of aromatics through hydrogen transfer reactions which facilitated the dehydroxylation and demethoxylation of phenols. The present work provides a promising approach of converting biomass and plastic wastes directly into jet fuel range hydrocarbons by using green inexpensive carbon-based catalysts.

Jet fuel range hydrocarbons production through competitive pathways of hydrocracking and isomerization over HPW-Ni/MCM-41 catalyst

To promote hydrocracking and isomerization activities of bifunctional catalyst for the conversion of methyl palmitate into jet biofuel, phosphotungstic acid (HPW) loaded on Ni/MCM-41 catalyst enhanced strong acidity to strengthen conversion pathways of hydrocracking and isomerization. In the bifunctional catalytic system, Ni catalyzed hydrodeoxygenation and dehydrogenation of methyl palmitate to produce 1-pentadecene, while acid sites catalyzed further conversion of 1-pentadecene to produce jet fuel range hydrocarbons. Quantum chemistry calculation showed that activation energy in chemisorption process of 1-pentadecene onto acid sites significantly reduced from 203.9 kJ/mol with MCM-41 to 81.6 kJ/mol with HPW. Since bond order of β-scission site in 1-pentadecene over HPW was 0.93% lower than that over MCM-41, and Hirshfeld atomic charge of carbenium ion in 1-pentadecene over HPW (0.0722) was much higher than that over MCM-41 (0.0473), HPW showed better catalytic activities than MCM-41 in both hydrocracking and isomerization processes. The overall selectivity of jet biofuel increased to 86.1% with 47.1% n-alkane selectivity and 8.3% iso-alkane selectivity, due to improved strong acid density from 0.563 to 0.730 mmol/g over 20% HPW-Ni/MCM-41 catalyst.

Core–Shell Pt@Ir Nanothorns on Carbon Fiber Paper Electrodes for Carboxylic Acid Valorization via Kolbe Electrolysis

Valorization of biomass-derived carboxylic acids into drop-in fuels with the input of renewably sourced electricity is promising for a clean and sustainable energy future. Herein, self-supporting core–shell Pt@Ir nanothorns on 3D porous carbon fiber paper anodes have been employed for the electrocatalytic upgrading of carboxylic acids into fuel-range hydrocarbons. The core–shell anode is synthesized by electrodepositing Pt nanothorns on carbon fiber paper followed by galvanic deposition of a thin layer of Ir nanothorns on the surface. Pt@Ir exhibited a remarkably higher yield (49.5%) and Faraday efficiency (62.3%) for hydrocarbon production as compared to that of benchmark commercial Pt/C. The anode also has good recyclability with little activity loss after five successive runs.

Comparison of hydrocarbons synthesis mathematical models for dimethyl ether catalytic transformation process

A comparison of mathematical models applicable for hydrocarbons formation process by catalytic transformation of dimethyl ether is discussed in the article. Dimethyl transformation is complex catalytic process used for aliphatic, aromatic hydrocarbons and olefins formation. The process can be realized for transformation of renewable and waste organic resources into fuel range hydrocarbons. Proper mathematical modelling for this complex process can play a driver role for process productivity intensification. A mathematical models proposed by different authors are discussed and compared to self-developed Eley-Rideal based model. Advantages and models limitations are discussed in the article.

Biomass-derived CO2 rich syngas conversion to higher hydrocarbon via Fischer-Tropsch process over Fe–Co bimetallic catalyst

Biomass-derived syngas (CO2 + CO + H2) has emerged as a potential non-fossil fuel source to yield transportation fuel via Fischer Tropsch Synthesis (FTS) reaction. Thus, the present study demonstrates the conversion of CO2 containing syngas into fuel range hydrocarbon via Fischer Tropsch Synthesis over Fe–Co bimetallic catalyst. The experimental tests were carried out in a fixed bed continuous reactor to investigate the effect of CO2 on CO/CO2 conversion. Accordingly, obtained data were validated by FTS kinetic model for a plug flow reactor. It was found that the unique combination of Fe and Co bimetallic catalyst facilitates both FTS and water gas shift (WGS) reaction simultaneously that helps to convert CO2 along with CO. It was also observed that the presence of iron in the catalyst helps in conversion of CO2 into hydrocarbons, only when a particular concentration of CO2 in syngas is reached, i.e., critical ratio RC (CO2/CO + CO2) due to the occurrence of reverse water gas reaction (RWGS) which varies with the temperature and the feed gas composition (H2/CO/CO2 molar ratio). At 240 °C and hydrogen deficient condition, the critical ratio was measured to be 0.74 whereas for hydrogen balanced condition, it was measured 0.6. The kinetic model developed in the present study predicted trends for % CO conversion, % carbon conversion, and % CO2 conversion which is applicable for a wide range of critical ratio RC (CO2/(CO + CO2) = 0 to 1). The model also predicted that a positive conversion of CO2 could be achieved at lower CO2 concentration by increasing the reaction temperature. At 260 °C and 280 °C, the value of Rc were 0.31 and 0.18 were measured.

Experimental investigations on olefin to paraffin ratio in Fischer-Tropsch products using syngas of low Ribblet ratio

Biosyngas generated from gasification of agricultural and forest wastes can be utilized as feed in a Fischer-Tropsch reaction after raising its Ribblet ratio (H2/(2CO+3CO2)) to unity through energy-intense steps of Water-Gas-Shift reaction and carbon dioxide removal. The direct utilization of raw biosyngas with low Ribblet ratio is a sustainable approach for the production of carbon-neutral synthetic fuel from waste biomass. This work investigates the olefin to paraffin ratios in C2 -C3 range of hydrocarbons among the Fischer-Tropsch products under different process conditions. A deviation from the classical Anderson-Schulz-Flory (ASF) distribution for enhancing product selectivity towards fuel range hydrocarbons, is possible due to the higher activity of C2 olefins in various secondary reactions. The investigations in this study also indicate the presence of equilibrium in the ratio of bulk C3 (olefin + paraffin) / C2 (olefin + paraffin) irrespective of reaction feed composition. A laboratory prepared 0.5Fe/ComesoHZSM-5 catalyst was used with model biosyngas of 0.6, 0.4, and 0.2 Ribblet ratios as feed and the reaction were performed in a continuous fixed-bed reactor in the temperature range of 220–260 °C and space velocities of 1800-3400 mLh−1gcat−1. The experimental results show a similar trend in carbon monoxide conversion per gram of catalyst for Ribblet ratios of 0.6 and 0.4. The olefin to paraffin ratio in lower hydrocarbon range (n ≤ 5) for various carbon monoxide conversions is used as an indicator of chain growth efficiency in Fischer-Tropsch synthesis.

Chemical compositions and properties of lignin-based jet fuel range hydrocarbons

Sustainable aviation fuels remain the only near, mid, and likely long term solution for lowering the carbon emissions of commercial and military aviation. Determination of sustainable aviation fuel’s chemical compositions and prediction of their properties is a critical first step for further research and development leading to the final certification process. Our analytical results showed that the lignin-based jet fuel (US patent 9,518,076 B2) consists of mainly paraffinic hydrocarbon species. They can be further classified into several classes, including n-paraffins, iso-paraffins, mono-, di-, and tri-cycloparaffins of which the majority contains carbon numbers in the range of 7–20. The very high concentration of polycycloparaffins along with the relatively low content of monocycloparaffins contribute to the high boiling point of the sample. Reducing the boiling point will require cracking and further hydrotreating of the lignin-based jet fuel range hydrocarbons to increase monocycloparaffins ratio close to the coal-based jet fuel compositions (e.g., JP-900). Also, this lignin-based jet fuel contains very low aromatics concentration which illuminates favorable energy content, energy density, possible low emissions, and very high-performance characteristics might meet drop-in specifications.

Continuous hydroprocessing of microalgae biodiesel to jet fuel range hydrocarbons promoted by Ni/hierarchical mesoporous Y zeolite catalyst

To simulate the industrial production of jet fuel range hydrocarbons, the hydroprocessing of Nannochloropsis oceanica microalgae biodiesel over a nickel-based hierarchical mesoporous Y (meso-Y) zeolite catalyst in a continuous process was investigated. The goal was to optimize two of the key parameters involved in hydroprocessing process, i.e., the reaction temperature and feedstock injection rate, to improve the biodiesel conversion and product selectivity, especially to iso-alkanes. A microalgae biodiesel conversion of 91.5% with a selectivity to jet fuel range hydrocarbons of 56.2% was obtained for a feedstock injection rate of 0.02 mL/min at 275 °C over Ni/meso-Y zeolite catalyst (total acid density = 3.08 mmol/g and BET surface area = 599.57 m2/g) in a fixed bed continuous hydroprocessing system. In addition, an isomerization ratio of 46.4% was achieved and attributed to the optimized reaction conditions, as well as to the shape selectivity exhibited by the catalyst. XRD performed for the used catalyst revealed unchanged crystallinity of the zeolite while a sintering process was noted for Ni nanoparticles whose crystallite size increased from 25 to 54 nm during hydroprocessing at 275 °C. FTIR detected functional groups of CH2 (final saturated hydrocarbons), CHO (intermediate aldehydes), and CC (intermediate olefins), which were generated over catalyst after reactions. SEM and EDS showed that carbon element (22.9 wt%) uniformly distributed over catalyst after reaction at 275 °C due to efficient conversion.

Effects of Zeolite Supports on the Production of Fuel-Range Hydrocarbons in the Hydrotreatment of Various Vegetable Oils with Platinum-Based Catalysts.

The effects of catalyst supports on catalyst performance in the hydrotreatment of vegetable oils (to produce fuel-range hydrocarbons such as gasoline, jet fuel, and diesel) were investigated, using three types of zeolites (ZSM-5, HY, and zeolite-beta (BEA)) that differ in their silica/alumina ratios. Structural characterization of the catalysts was performed using ICP, XRD, BET, TEM, and NH₃-TPD. Catalytic tests were carried out in a fixed-bed reaction system at 400 °C and 50 bar. In the hydrotreatment of soybean oil, higher conversions into liquid hydrocarbons and fuel-range hydrocarbons were found when supports with lower Si/Al₂ ratios were used. Specifically, Pt/BEA (Si/Al₂ = 25) produced the highest conversion into liquid products (72%) and the highest selectivity for hydrocarbons in the jet fuel (46%) and diesel (51%) fuels. A Pt loading amount of 3 wt% in this catalyst gave the best catalytic performance because of the optimal balance between acidic and metallic sites. Finally, the kinds of vegetable oils in the hydrotreatment performance over Pt/BEA (Si/Al₂ = 25) affected the order; waste-cooking oil > jatropha oil > soybean oil.

Oligomerization of lower olefins to fuel range hydrocarbons over texturally enhanced ZSM-5 catalyst

Abstract Zeolites with various pore structures and sizes such as microporous ZSM-5, desilicated ZSM-5, Beta zeolite and ZSM-48 were investigated as catalysts in the oligomerization of propylene and 1-hexene to fuel-range hydrocarbons. Mesoporous ZSM-5 was prepared via a post-synthesis alkaline treatment. Physicochemical properties of the zeolite catalysts were characterized by XRD, XRF, SEM, TEM, MAS NMR, BET, and NH3-TPD techniques to analyze the crystallinity, element composition, morphology, textural properties as well as acidity distribution. The catalyst characterization confirmed that NaOH post-treatment by mild desilication is an effective method to tune the pore structure of medium pore ZSM-5 zeolite by introducing mesoporosity without damaging the microporous structure. Enhanced activity and selectivity to jet fuel/diesel range (C12) products of ˜90% and 55% respectively was achieved over a modified ZSM-5 catalyst at optimum reaction conditions of 220 °C and weight hourly space velocity (WHSV) of 4 h−1 in the oligomerization of 1-hexene. Good selectivity to gasoline-range hydrocarbons with high octane number was achieved over modified ZSM-5 in the oligomerization of propylene. The spent catalysts were characterized by thermogravimetric and NH3-TPD analyses which confirmed that carbonaceous deposits were prevalent inside the micropores of the catalysts but its effects were less severe on the modified ZSM-5.

Conversion of Biomass-Derived Furanics to Fuel-Range Hydrocarbons: Use of Palm Oil Empty Fruit Bunches

In the search of hydrocarbon fuels derived from biomass, the increase in the chain length with the elimination of oxygenated species is a hard task. The simultaneous conversion of furfural and cyclopentanone to fuel range hydrocarbons has been investigated on a series of solid base catalysts. Furfural represents the family of sugars, typically obtained from the hemicellulose biomass fraction by different catalytic routes. Cyclopentanone can be readily obtained from the catalytic conversion of furfural via Piancatelli ring-rearrangement under reducing conditions. Aimed to enlarge the carbon chain length of these oxygenates, the aldol-condensation reaction between furfural and cyclopenanone was studied over MgAl mixed oxides, among which the MgAl-3 mixed oxide exhibited the best catalytic activity to produce C10–C14 oxygenates, a suitable range for transportation fuel precursors (C7–C15). After this C–C coupling reaction, the large oxygenates were successfully upgraded via hydrodeoxygenation on carbon-supported Ru and Pd nanoparticles to produce a mixture of linear alkanes and saturated cyclic hydrocarbons, which in practice would be direct drop-in components for transportation fuels. As an illustration of the potential implementation of this strategy for biofuel production, palm oil empty fruit bunches were experimentally evaluated using different acid pretreatments to extract the furfural, which was further employed to perform the aldol-condensation reactions. It was found that the proposed catalytic strategy is an environmentally-friendly route to add value to the palm oil industry wastes by producing value-added chemicals and fuel precursors.

Sulfonated mesoporous Y zeolite with nickel to catalyze hydrocracking of microalgae biodiesel into jet fuel range hydrocarbons

To promote catalytic performances of Ni-based mesoporous Y (meso-Y) zeolite in the hydrocracking conversion of microalgae biodiesel to jet fuel range hydrocarbons, 3-mercaptopropyltrimethoxysilane was utilized as sulfonating agent to improve the acid density of meso-Y zeolite. The physiochemical properties of sulfonated meso-Y zeolite were characterized via temperature-programmed desorption of ammonia, X-ray diffraction, Fourier-transform infrared spectroscopy, energy dispersive spectroscopy, scanning electron microscopy, and N2 physisorption. It was detected that sulfonic acid groups (-SO3H) composed of SO and SO bonds were successfully grafted onto meso-Y zeolite framework. The strong acid density significantly increased from 0.31 mmol/g to 1.21 mmol/g when meso-Y zeolite was treated with 0.38 mL/g sulfonating agent. The crystalline interplanar spacing of meso-Y zeolite expanded with a shifted position (2θ) of X-ray diffraction peak from 15.72° to 15.70°. The enhanced hydrocracking capacity of 10% Ni/sulfonated meso-Y zeolite catalyst resulted in improvements in microalgae biodiesel conversion (from 82.1% to 99.7%) and jet fuel range alkane selectivity (from 31.2% to 52.3%).

Aggregate shape determination via light scattering by aligned and randomly oriented polydisperse aggregates

We present calculations of light scattered by simulated aligned and randomly oriented fractal aggregates of touching spheres. The alignment by an applied electric field is in the direction yielding the minimum energy associated with the polarizability of the aggregate. This direction is also within a few degrees of the direction associated with the smallest inertial eigenvalue. Aggregates were generated to have a fractal dimension of 1.78 (characteristic of diffusion–limited cluster-cluster aggregation) and to simulate the range of aggregate sizes (30 to 2000) and size distributions for post-flame generated soot by a range of hydrocarbon fuels. More nearly monodisperse aggregates were also generated to simulate the size distributions obtained via mobility or mass classification. We show that a ratio of slopes computed from small angle light scattering intensities (Guinier plots) is related to the shape parameter A31, which is the ratio of the largest to the smallest principle radii of gyration of the inertia tensor. A geometric interpretation of the overall shape is presented based on the semi-axes of an ellipsoid. Results on the correlation between the maximum structure factor ratio {S(q)}a/ {S(q)}r for the monodisperse and polydisperse clusters and the average value of A31 indicate that light scattering measurements in the q range of fractal behavior would also be feasible for shape characterization. Our calculations indicate that light scattering measurements have a good potential for characterizing aggregate shape with an advantage of being more sensitive to shape than mobility measurements.

Effects of Sugars, Furans, and their Derivatives on Hydrodeoxygenation of Biorefinery Lignin‐Rich Wastes to Hydrocarbons

Hydrodeoxygenation of biorefinery lignin-rich wastes to jet fuel hydrocarbons offers a significant opportunity for enhancing the overall operational efficiency, carbon conversion efficiency, economic viability, and sustainability of biofuels production. However, these wastes usually mainly contain lignin with sugars, furans, and their derivatives as "impurities". Although several factors, including reactant structure, solvents, or the decreased ratio of catalyst to reactant, could be responsible for the jet fuel hydrocarbons yield loss, we found evidence that glucose, xylose, and 5-hydroxymethylfurfural dramatically decreased conversion yields. For example, xylose and glucose lowered the final hydrocarbon yield by 78 and 63 %, respectively. The results revealed that these compounds could suppress metal catalysts and inhibit lignin depolymerization and hydrodeoxygenation (HDO) reactions thus decrease yields of jet fuel range hydrocarbons from biomass-derived lignin. The first-principles calculations and TGA results from spent catalysts validated these findings.