Gasoline Range Hydrocarbons Research Articles

Untangling the role of the organosilane functional groups in the synthesis of hierarchical ZSM-5 zeolite by crystallization of silanized protozeolitic units

Abstract Crystallization of hierarchical ZSM-5 zeolite has been performed under hydrothermal conditions from silanized protozeolitic units. The role of amine and phenyl groups present in the organosilanes, as well as the use of dipodal silanization agents, on the creation of mesoporosity in the zeolite samples has been investigated. The presence of amine groups and dipodal moieties in the organosilane increases their interactions with the protozeolitic nanounits in the gel, which results in hierarchical zeolites showing enhanced secondary porosity and a higher degree of modification of the textural properties. Nevertheless, dipodal organosilanes hinder strongly the aggregation of the nanounits, leading to non-completely crystalline materials. In contrast, the combination of phenyl and amine groups into a single organosilane has shown to be effective for the generation of more uniform mesopores. Thus, N-(2-N-Benzylaminoethyl)-3-aminopropyltrimethoxysilane (Ph-2A) has been found as the best silanization agent, affording a hierarchical zeolite with a narrow mesopore size distribution and a high concentration of strong Bronsted acid sites. Moreover, during LDPE catalytic cracking in TGA tests, the latter material allowed the conversion of the polymer to occur in a narrow temperature range as a consequence of its more uniform acid and textural properties. Likewise, this sample exhibited a high activity in LDPE cracking at 340 °C using a laboratory scale reaction system to produce mainly gasoline-range hydrocarbons and light olefins.

Ni, Zn and Fe hydrotalcite-like catalysts for catalytic biomass compound into green biofuel

Abstract In this study, the deoxygenation pathway was proposed to eliminate oxygen species from biomass-derived oil, thereby producing a high quality of hydrocarbon chains (green fuel). The catalytic deoxygenation reaction of bio-oil model compound (oleic acid) successfully produced green gasoline (C8–C12) and diesel (C13–C20) via activated hydrotalcite-derived catalysts (i.e. CMgAl, CFeAl, CZnAl and CNiAl). The reaction was performed under inert N2 condition at 300 °C for 3 h, and the liquid products were analysed by GC–MS and GC–FID analyses to determine the hydrocarbon yield and product selectivity. The activity of the catalysts towards the deoxygenation reaction presented the following increasing order: CNiAl > CMgAl > CZnAl > CFeAl. CNiAl produced a hydrocarbon yield of up to 89 %. CNiAl demonstrated the highest selectivity with 83 % diesel production, whereas CMgAl showed the highest gasoline selectivity with 30 %. These results indicated that catalysts with a high acidic profile facilitate C–O cleavage via deoxygenation, producing hydrocarbons (mainly diesel-range hydrocarbons). Meanwhile, highly basic catalysts exhibit significant selectivity towards gasoline-range hydrocarbons via cracking and lead to the occurrence of C–C cleavage. The large surface area of CNiAl (117 m2 g−1) offered high approachability of the reactant with the catalyst’s active sites, thereby promoting high hydrocarbon yield. Consequently, the hydrocarbon yield and selectivity of the deoxygenation products were predominantly influenced by the acid–base properties and structural behaviour (porosity and surface area) of the catalyst.

Selective Fischer-Tropsch synthesis for gasoline production over Y, Ce, or La-modified Co/H-β

Selective Fischer-Tropsch synthesis has been carried out over a series of Co/H-β catalysts to investigate the influence of rare-earth metal ions promotion on the synthesis of gasoline-range hydrocarbons (GRHs, C5–C12 hydrocarbons). H-β zeolite was doped with rare-earth metal ions, specifically Y3+, Ce3+ and La3+, by an ion-exchange method. The resulting catalysts were characterized by different methods, namely ICP-OES, BET, XRD, TEM, STEM-EDS, H2-TPR, NH3-TPD, CO-TPD and TG. It was found that the addition of Y3+ improved the dispersion of active components over the Co/H-β catalyst, while doping with Ce3+, having the ability to change its valence state as well as the number of oxygen vacancies of the support, enhanced the catalyst reducibility. However, the addition of La3+ tended to cause agglomeration of the active particles due to its large ionic radius. Performance tests showed that the Co/Y-β and Co/Ce-β catalysts achieved higher CO conversions. Due to the moderate acidity and the enhanced CO-metal bonding, the Co/Y-β catalyst exhibited optimal GRHs selectivity of 49% with a yield of 41.4% at 260 °C, 2 MPa, H2/CO = 2, and 1064 h−1. More light hydrocarbons were produced after ion-exchange with La3+ because new strongly acidic sites were formed in the zeolite, leading to low GRHs production.

Transportation fuel from plastic wastes: Production, purification and SI engine tests

Thermal pyrolysis of HDPE, LDPE, PP, PS, PET and PUR plastic wastes were performed in a batch reactor equipped with a temperature controlled reflux and the yields of pyrolysis oils and liquid fuels suitable for transportation were determined. The gasoline fractions were investigated by GC-MS and tested in a traditional spark-ignition engine without any modifications or fuel blending. Fuel consumption and exhaust gas emission (NOx, CO) were measured and compared to a commercial fuel (gasoline, RON = 95). PS generated 70.5% gasoline range hydrocarbons from the solid waste, followed by PP with 42.1%, LDPE with 40.8% and HDPE with 37.3%. Liquid product was not observed during PET pyrolysis. The engine was easily running with neat gasoline fractions obtained from HDPE, LDPE, PP and PS distillation; however, it was not able to start the engine with the neat dehydrated PUR distillate. The volumetric fuel consumption was reduced by 9.1–9.4% in case of PS compared to commercial gasoline (RON = 95) but the NOx emission was increased by 82–147%. Fuel consumption reduction was noticeable at HDPE, LDPE and PP as well. PS gasoline decreased by 91–96%, while HDPE, LDPE and PP more likely increased the CO emission of the engine compared to commercial gasoline.

Conversion of methanol to aromatics over ZSM-5/11 intergrowth Zeolites and bimetallic Zn-Cu-ZSM-5/11 and Ga-Ag-ZSM-5/11 catalysts prepared with direct synthesis method

Catalytic conversion of methanol to gasoline range hydrocarbons, especially aromatics was carried out in a fixed bed reactor over nano-crystal composite H-ZSM-5/11 zeolite synthesized by hydrothermal method. The metals of Zn, Cu, Ga and Ag as bimetallic Zn-Cu and Ga-Ag with different concentrations (3: 2, 5: 3) and (1:1, 3:2) respectively were selected for loading into the prepared zeolite catalysts. Direct synthesis method was used for incorporating metals. Prepared zeolites were characterized by XRD, SEM, TEM, N2 adsorption-desorption, ICP-OES, NH3-TPD and FT-IR. After incorporation of metal species into the zeolites framework, the particles crystalline size was reduced, the intercrystalline porosity was increased, causing the formation of new moderate acid sites. The catalytic results illustrated that the incorporation of metal species enhanced the activity and catalyst stability in MTA reaction. BTX yield in ZSM-5/11 reached up at 23.5% to 30.4% and 25.88% with Zn-Cu-ZSM-5/11(1) and Ga-Ag-ZSM-5/11(1), respectively whereas heavier aromatics production reduced. Also, the comparison of catalysts with different metals content showed that due to improvement in structure and properties, low metal content zeolites have better performance in converting methanol to aromatics. The catalytic conversion of methanol to the hydrocarbons, particularly aromatics, was investigated with bimetallic Zn-Cu-ZSM-5/11 and Ga-Ag-ZSM-5/11 catalysts. Incorporated metals replaced parts of the conventional acid sites and formed some new acid sites in the zeolites. The change in acidity and mesoporosity significantly improved aromatization reaction and catalyst stability

Hydrodeoxygenation of sorbitol to gasoline-range hydrocarbons over Pt, Pd, Rh, Ru, Ni catalysts supported on tungstated alumina

Catalytic properties of the tungstated alumina (WA) supported catalysts with different nature and content of active metal (Pt, Pd, Rh, Ru, Ni) were studied in the continuous flow hydrodeoxygenation of sorbitol at a temperature of 653 K, a pressure of 4.0 MPa, and weight hourly space velocity (WHSV) of 1.0 h−1. The catalysts were characterized by N2 physical adsorption, H2-TPR, CO chemisorption, TEM, and NH3-TPD. It was found that all catalysts provide complete conversion of sorbitol with the formation of C5–C7 hydrocarbons as the main products which include n-alkanes, cycloalkanes, and isoalkanes. The yield of С5–С7 hydrocarbons after 1 h of the reaction increases from 42 to about 74 mol% in a series of catalysts: 5% Ni/WA < 0.5% Ru/WA < 0.5% Pd/WA < 0.5% Rh/WA < 0.5% Pt/WA. The calculated value of the research octane number (RON) for the С5–С7 mixture rises from ca. 62 to 80 in a series of catalysts: 0.5% Pt/WA < 0.5% Pd/WA < 0.5% Rh/WA < 5% Ni/WA < 0.5% Ru/WA. The stable yield and RON values (no less than 57 mol% and 70, respectively) of С5–С7 hydrocarbon mixture are achieved during hydrodeoxygenation over the 0.5% Pd/WA catalyst for 8 h.

Enhancing Gasoline Range Hydrocarbons by Catalytic Co-pyrolysis of Rice Husk with Low Density Polyethylene (LDPE) Using Zeolite Socony Mobil#5(ZSM-5)

In the present work, catalytic co-pyrolysis of rice husk with low density polyethylene (LDPE) was investigated to enhance the amount of gasoline range hydrocarbons in the bio-oil. Zeolite Socony Mobil#5(ZSM-5) was used as catalyst. The specific surface area, pore volume and the average pore size of ZSM-5 were evaluated to be 418.041 m2/g, 0.227 cc/g and 1.628 nm respectively. Optimum temperature for obtaining highest bio-oil yield for non-catalytic co-pyrolysis was 600 °C, resulting in yield of 51.26 %. For catalytic co-pyrolysis, the optimum temperature was 500 °C with a bio-oil yield of 38.87 %. H/C ratio of gasoline range hydrocarbon oil obtained by catalytic co-pyrolysis was 1.21, while the oxygen content was 2.51 %.The results of GC HRMS revealed that, the gasoline range hydrocarbon oil obtained by catalytic co-pyrolysis contained 17.65 % Cycloalkanes, 6.131 % alcohols, 31.75 % esters and 32.68 % alkenes.

Catalytic microwave-assisted pyrolysis of plastic waste over NiO and HY for gasoline-range hydrocarbons production

Recovering fuels or chemicals from plastic waste via pyrolysis is an innovative and promising route for both energy saving and refuse elimination. In this study, catalytic microwave-assisted pyrolysis of low-density polyethylene (LDPE) was performed to simultaneously improve yield and quality of gasoline-range products. NiO and HY zeolite were respectively used as in-situ and ex-situ catalysts in a two-stage pyrolysis-catalysis system. The results showed that the optimum pyrolysis and catalysis temperatures were 500 °C and 450 °C, respectively, with 56.53 wt% oil product and 93.80% gasoline-range fraction achieved. The content of high-octane-number compounds, primarily aromatics and isomerized aliphatics, increased from 23.5% to 80.4% as HY to LDPE ratio rose from 0 to 1:5. The optimized balance between oil yield and oil quality was obtained at the HY to LDPE ratio of 1:10. The presence of NiO during co-catalysis slightly decreased the oil yield by 5.3–8.5 wt%. Meanwhile, the production of aromatics was promoted obviously while the yield of normal aliphatics was inhibited, which were both favorable to improve the octane number of the oil product. The improved performance of co-catalysis could be related to the suitable hydrogen abstraction ability of NiO, which produced enormous alkenes. Subsequently, cycloalkenes and aromatics were synthesized through Diels-Alder reactions over the catalysis of HY. This co-catalysis approach in the microwave reactor provides a potentially profitable way to convert plastic waste into high-quality and high-yield gasoline fuels.

Conversion of Stearic Acid into Bio-Gasoline over Pd/ZSM-5 Catalysts with Enhanced Accessibility

Palladium supported on nanocrystalline ZSM-5 (n-ZSM-5, Si/Al = 32) and hierarchical ZSM-5 (h-ZSM-5) with different acidity (Si/Al = 33, 51, 122) were tested in the liquid-phase conversion of stearic acid under nitrogen atmosphere (6 bar). The incorporation of Pd into ZSM-5 zeolite increased significantly the share of gasoline in the reaction products due to the promotion by this metal of both decarboxylation and hydrogen transfer reactions. Likewise, the Pd nanoparticles dispersed over the zeolitic support favored the conversion of light olefins formed by end-chain cracking reactions into gasoline-range hydrocarbons according to an oligomerization/cyclization/aromatization pathway. Additionally, Pd/h-ZSM-5 gave rise to higher conversion and selectivity towards gasoline than Pd/n-ZSM-5, due mainly to the enhanced accessibility and improved Pd dispersion achieved when using the hierarchical zeolite. The decrease in the Si/Al atomic ratio in Pd/h-ZSM-5 samples resulted in a rise in the stearic acid conversion, although it was lower than expected. This finding denotes that, for supports with high acid sites concentration, the Pd availability became the limiting factor as the metal was loaded in similar amounts in all catalysts. Finally, the increase of the reaction temperature with the Pd/h-ZSM-5 (122) catalyst augmented both stearic acid conversion and gasoline selectivity, since it enhanced the conversion of the light olefins, formed as primary cracking products, into liquid hydrocarbons. Therefore, it can be concluded that Pd supported on hierarchical ZSM-5 zeolite is a convenient catalyst for obtaining bio-gasoline from oleaginous feedstock.

Co- and Fe-containing Silica-based Catalysts Synthesized in Subcritical Water

A study of the structure and catalytic properties of the cobalt- and iron-containing catalysts synthesized by the subcritical deposition in the water medium was performed in the current work. The catalyst synthesis was carried out at a temperature of 200 °C and a total pressure of 7.5 MPa using silica as support. The catalytic activity of the synthesized materials was studied in the liquid-phase Fischer-Tropsch synthesis. The study of catalyst structure and composition showed that the use of silica as catalyst support allows the formation of Co- and Fe-containing particles consisted of metal oxides. Testing of the synthesized catalysts in liquid phase Fischer-Tropsch synthesis showed that Co-based catalyst allowed the formation of gasoline-range hydrocarbons. It is noteworthy that Co/SiO2 showed higher selectivity towards the formation of linear C5-C8 hydrocarbons. In the case of Fe-containing catalyst, the formation of a significant amount of oxygenates (C3-C4 alcohols) was found.

Light Hydrocarbon Geochemistry: Insight into Mississippian Crude Oil Sources from the Anadarko Basin, Oklahoma, USA

The Mississippian limestone is a prolific hydrocarbon play in the northern region of Oklahoma and the southern part of Kansas. The Mississippian reservoirs feature variations in produced fluid chemistry usually explained by different possible source rocks. Such chemical variations are regularly obtained from bulk, molecular, and isotopic characteristics. In this study, we present a new geochemical investigation of gasoline range hydrocarbons, biomarkers, phenols, and diamondoids in crude oils produced from Mississippian carbonate and Woodford Shale formations. A set of oil samples was examined for composition using high-performance gas-chromatography and mass-spectrometry techniques. The result shows a distinct geochemical fingerprint reflected in biomarkers such as the abundance of extended tricyclic terpanes, together with heptane star diagrams, and diamantane isomeric distributions. Such compounds are indicative of the organic matter sources and stages of thermal maturity. Phenolic compounds varied dramatically based on geographic location, with some oil samples being depleted of phenols, while others are intact. Based on crude oil compositions, two possible source rocks were identified including the Woodford Shale and Mississippian mudrocks, with a variable degree of mixing reported. Variations in phenol concentrations reflect reservoir fluid dynamic and water interactions, in which oils with intact phenols are least affected by water-washing conversely and crude oils depleted in phenols attributed to reservoir water-washing. These geochemical parameters shed light into petroleum migration within Devonian-Mississippian petroleum systems and mitigate geological risk in exploring and developing petroleum reservoirs.

Interaction of three categories of tyre waste during co-pyrolysis: Effect on product yield and quality

Disposal of huge generation of non-biodegradable waste tyre poses a big environmental threat today. Energy recovery through thermo-chemical route like pyrolysis has been emerging as an important research area. Though pyrolysis of individual tyre waste was investigated by various researchers, the impact of the interaction of different type of tyres in the waste mix on the pyrolysis process, product yield and properties needs further research. This work was taken up to bridge this gap. In this work, a mix of three different tyre waste; namely light vehicle tyre (LVT), medium vehicle tyre (MVT) and heavy vehicle tyre (HVT), was pyrolysed at 750 °C with varying proportions to assess the synergistic effect on the products yield and their characteristics. Higher fraction of LVT in the mix reduced the degradation temperature of the mixed tyre due to the dominant presence of natural rubber (NR). Higher fraction of HVT increased the degradation temperature due to greater presence of BR. Also, a higher amount styrene in the mix caused larger fractional residue. MVT produced the highest char yield as it had highest ash content and more styrene butadiene rubber (SBR) and lowest oil yield due to very less presence of NR and butadiene rubber (BR). HVT produced the lowest char and highest oil yields due to the presence of NR and BR and low ash. The experimental results showed a higher solid (char) yield than that predicted. The gas yield was less than that predicted. The oil yield, however, showed a much lower synergistic effect. At degradation >50%, the gas primarily consisted of hydrogen and methane while other gases such as C2-C6, CO and CO2 were present in small quantities. The oil fractions obtained from the pyrolysis of waste tyre showed a strong similarity with the gasoline range hydrocarbons. Produced char with a high surface area may be activated further and used as activated carbon in waste water treatment.

Thermal pyrolysis of high density polyethylene (HDPE) in a novel fixed bed reactor system for the production of high value gasoline range hydrocarbons (HC)

Pyrolysis is a promising thermolysis technique to recover valuable oils and light hydrocarbons (HC) with high yields from plastic solid waste (PSW). In this work, thermal pyrolysis of high density polyethylene (HDPE) with the aim of producing gasoline range hydrocarbon oils, has been carried out in a novel fixed bed (batch) reactor. The pyrolysis of HDPE has been conducted between 500 to 800 °C in the presence of nitrogen as an inert carrier gas media to produce liquid fuel oil, gaseous products and solid char. The optimum temperature of obtaining maximum oil product yield (70%) was 550° C. A comprehensive gas chromatography (GC) analysis of the liquid and gaseous products was conducted to quantify high molecular weight individual HC components. Moreover, light molecular weight HC constituting the gaseous fraction were identified. A chemical kinetic analysis of the cracking reactions, was performed to investigate the reaction mechanism of yielding the maximum oil product. The oil product recovered had a high proportion of aliphatic HC especially in the range of C8 to C12, whilst aromatic HC were of lower proportion. The carbon number of the pyrolysis oil was noted to increase proportionally with the increasing operating temperature. The gaseous product had a high percentage (> 70%) of C2 to C4 HC, which was attributed to the high activity of carbon/carbon (C-C) chain scission reaction.

Solvent-free anchoring nano-sized zeolite on layered double hydroxide for highly selective transformation of syngas to gasoline-range hydrocarbons

Nano-sized zeolites (NZs) were anchored on the layered double hydroxide consisting of cobalt and aluminum (Co-Al-LDH) using a solvent-free synthesis method (denoted as Co-Al-LDO-NZs). During the synthesis process, Co-Al-LDH was not only employed as a substrate for the growth of nano-sized zeolites but also acting as Al sources to participate in the formation of acid sites in the zeolite. The well-designed catalyst was used as a bifunctional catalyst for highly selective production of gasoline-range hydrocarbons from syngas through Fischer-Tropsch (FT) synthesis. Benefiting from the unique architecture of Co-Al-LDO-NZs, long-chain hydrocarbons formed on the active FT catalyst could diffuse to the zeolites surface, where hydrocracking and isomerization occurred. Furthermore, different from the traditional zeolite-supported FT catalyst, the nanoscale zeolite in Co-Al-LDO-NZs efficiently suppressed the over-cracking of hydrocarbons, lowering the selectivity of undesirable light hydrocarbons (CH4 and C2–C4 alkanes).

High-Quality Gasoline Directly from Syngas by Dual Metal Oxide-Zeolite (OX-ZEO) Catalysis.

Despite significant efforts towards the direct conversion of syngas into liquid fuels, the selectivity remains a challenge, particularly with regard to high-quality gasoline with a high octane number and a low content of aromatic compounds. Herein, we show that zeolites with 1D ten-membered-ring (10-MR) channel structures such as SAPO-11 and ZSM-22 in combination with zinc- and manganese-based metal oxides (Zna Mnb Ox ) enable the selective synthesis of gasoline-range hydrocarbons C5 -C11 directly from syngas. The gasoline selectivity reached 76.7 % among hydrocarbons, with only 2.3 % CH4 at 20.3 % CO conversion. The ratio of isoparaffins to n-paraffins was as high as 15, and the research octane number was estimated to be 92. Furthermore, the content of aromatic compounds in the gasoline was as low as 16 %. The composition and structure of Zna Mnb Ox play an important role in determining the overall activity. This process constitutes a potential technology for the one-step synthesis of environmentally friendly gasoline with a high octane number from a variety of carbon resources via syngas.

Correction to: Preparation and Characterization of Fe–Co/SiO2 Nanocatalysts for Gasoline Range Hydrocarbons Production from Syngas

The original version of this article unfortunately contained mistakes in the Supplementary information.

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.

Production of jet fuel and green diesel range biohydrocarbons by hydroprocessing of soybean oil over niobium phosphate catalyst

Drop-in biofuels are non-oxygenated biofuels composed by biohydrocarbons produced from different biomass. These drop-in biofuels (biogasoline, bio jet-fuel and green diesel) show a great importance due to their properties similar to those observed for fossil fuels. Lipids are one of the most important raw material used for deoxygenation reactions over special catalysts. In this work, niobium phosphate was investigated as catalyst in the production of drop-in biofuels from soybean oil, using mild experimental conditions. The performance of niobium phosphate was evaluated under different reaction time (3–5 h), catalyst amount (0–25%) and temperature (300–350 °C), using 10 bar H2. The composition of the liquid products was determined by gas chromatography coupled with mass spectrometry, and characterized by infrared spectroscopy. The optimization process led to high yields of hydrocarbons in the range of C9–C17. About 62% of bio-jet fuel, 40% of green diesel, and 18% of gasoline range hydrocarbons were obtained in a single reaction step. Their composition included mainly linear and branched alkanes as well as aromatics compounds. The pathways for the involved reactions are discussed.

Thermal stability of 2-thiadiamondoids determined by pyrolysis experiments in a closed system and its geochemical implications

The abundance of 2-thiadiamondoids is currently utilized to assess the extent of thermochemical sulfate reduction (TSR). However, these compounds are ultimately degraded to small molecules with increasing temperature in deep hot reservoirs, resulting in uncertainty in their use as a proxy to evaluate the extent of TSR. In this study, the thermal stability of 2-thiadiamondoids was determined from variations in their abundance upon pyrolysis at different temperatures using an oil enriched in thiadiamondoids. The results demonstrated that these compounds were generally stable at Easy%Ro ≤ 1.0, followed by partial destruction at Easy%Ro = 1.3–2.0 and intensive decomposition at Easy%Ro ≥ 2.0–2.3, suggesting the potential underestimation of the TSR extent at the highly mature to over mature stages. The thermal stability of 2-thiadiamondoids and diamondoids strongly depended on their cage numbers, which presented an increasing trend with higher cage numbers. However, diamondoids were far more stable than 2-thiadiamondoids and were still thermally stable even up to Easy%Ro = 1.8–2.3. The thermal stability of dibenzothiophenes (DBTs) showed a decreasing trend with increases in alkyl substituted carbon numbers. They were thermally stable at Easy%Ro ≤ 1.0–1.8 and can be seriously cracked at Easy%Ro ≥ 1.8–3.0. The C0-DBT and C1-DBTs were more stable than thiadiamondoids, but C3-DBTs showed the opposite trend. The thermal stability of gasoline range hydrocarbons showed a trend of CH4 > C2H6 > C3H8 > C4–5. CH4 and C2H6 were much more stable than diamondoids, while C3–5 hydrocarbons were only thermally stable at Easy%Ro ≤ 1.8–2.3 and severely degraded at Easy%Ro ≥ 2.6–3.0. The C3H8 and 2-cage diamantanes, C4–5 compounds and 1-cage adamantanes had a similar thermal stability. Therefore, to accurately assess the TSR extent should be made using thiadiamondoids, diamondoids and C0–1-DBTs, even gasoline range hydrocarbons, rather than thiadiamondoids alone, if gases are well preserved within petroleum reservoirs in the subsurface.

One-pot conversion of cellulose to liquid hydrocarbon efficiently catalyzed by Ru/C and boron phosphate in aqueous medium

Direct conversion of lignocellulose to fuels has been widely considered as one of most potential ways to produce renewable transportation fuels. In current study, 70.6% yield of gasoline-range hydrocarbons (C5 and C6 alkanes) was directly obtained from cellulose by using Ru/C and boron phosphate in aqueous medium. For conversion of cellulose to hydrocarbon, the main intermediates were sorbitol and its dehydration products, such as 1,4-, 1,5-, 2,5-sorbitans and isosorbide. The formation of isosorbide was undesirable due to its bis-tetrahydrofuranic moieties which are resistant to further hydrogenolysis to hydrocarbon. In current catalysis system, boron phosphate played a positive effect on formation of dehydration products from sorbitol. The hydrolysis process of boron phosphate in solution would probably delay both of the arrival of H+ with substrate and the increase of acidity in solution, which might reduce the formation rate of isosorbide. In addition, the coordination of boric acid with polyhydroxy compounds could also bring a barrier to the cyclodehydration of sorbitol to isosorbide. Therefore, in the presence of boron phosphate, the production of liquid hydrocarbon from cellulose can be significantly improved. Furthermore, the reaction pathway of cellulose transformation to C5/C6 alkanes via dehydration products of sorbitol was also proposed.