Fuel Processing Technology最新文献

Heating is the most straightforward means to achieve rapid, high-throughput production for thermal catalytic reactions, but photocatalysis reactions rarely use it because its intrinsic driving force depends on the effective separation of photogenerated charges, which generally shows little or sometimes negative dependence on temperature. Here we demonstrate that the heat generated by the photothermal conversion of Bi₂O₃ nanoparticles can be utilized to dramatically accelerate the photocatalytic decarboxylation of long-chain fatty acids to C_n-1 n-alkanes. Using high-boiling solvents to maximize reaction temperatures, C_n-1 n-alkane can therefore be obtained in very high concentrations (e.g., ∼0.5 M) in a single operation, 5 orders of magnitude higher than the previous both semiconductor photocatalytic and algal photoenzyme transformations limited in the range ∼ 1–10² μM. Comprehensive characterizations unveil that the heat from incident light enables the standing C-chain at low temperature down onto the surface of catalyst, which allows the photoinduced hole/electron to readily approach and react with the more strained C-COO⁻ bonds. This study manifests that the vast majority of incident light energy can be utilized in the form of heat to improve the reaction efficiency to as meet industrial output levels as possible.

The direct conversion of methane without an oxidant is an attractive approach to increase carbon efficiency. However, the reaction must be engineered appropriately. Herein, we propose a methane to olefins, aromatics, and hydrogen (MTOAH) system in which methane activation is promoted by co-feeding hydrocarbons generated from the Mo/HZSM-5 surface. The intentional separation of the catalyst and the gas-phase reaction at different temperatures (700 °C and 1020 °C) enables active and stable methane conversion via periodic reactions and regenerations. The linkage between MDA and MTOAH using 6Mo/HZSM-5 (30), which notably contributed to increasing the C2 production in MTOAH, was stabilized with 8.2% methane conversion during 49.5 h of the periodic CH₄ reaction-H₂ regeneration cycle. This study provides a new direction for achieving the efficient and carbon-neutral conversion of methane into useful chemicals.

A laboratory-scale fixed-bed column is employed to study the dynamic behavior of the carbon molecular sieve MSC CT-350 for CO₂/CH₄ separation. Breakthrough adsorption tests in single-component systems are carried out at different pressures (1, 3, 5, 6.5 and 8 bar) and constant temperature (20 °C). Moreover, an additional test is conducted with a 40% CO₂/60% CH₄ binary mixture at 3 bar. Desorption tests are performed by varying the purge-to-feed ratio (P/F) at 50%, 30% and 20%, optionally using a vacuum pump. Experimental results show that MSC CT-350 has a good CO₂ adsorption capacity for each pressure, considerably higher than CH₄. In the binary test, very slight differences are experimentally found in the adsorption kinetics and equilibrium adsorption capacity with respect to single-compound tests, which results equal to 2.16 mol kg⁻¹ for CO₂ and 0.302 mol kg⁻¹ for CH₄ at 3 bar, compared with 2.29 mol kg⁻¹ for CO₂ and 0.262 mol kg⁻¹ for CH₄ for the single-compoound counterparts. The time required for a complete regeneration decreases with the increase in purge flowrate and with the simultaneous use of the vacuum pump. Finally, CO₂ adsorption is a reversible process as the CO₂ adsorption capacity of the adsorbent is not significantly reduced when utilized in subsequent adsorption-desorption cycles.

In this study, a series of CuCoAl catalysts with different Cu/Co molar ratios were prepared from hydrotalcite-like precursors and then adopted for γ-valerolactone (GVL) hydrogenation to 1,4-pentanediol (1,4-PeD). By tuning the Cu/Co ratio in the CuCoAl catalysts and optimizing the reaction conditions, nearly 100% yield of 1,4-PeD was finally achieved with the Cu_0.2Co_0.8Al catalyst (Cu/Co = 1: 4) at 433 K and 4 MPa H₂. The high activity of the Cu_0.2Co_0.8Al catalyst was attributed to the existence of Cu-CoO_x synergistic active sites and the abundant surface acidity. The electron transfer from Cu to Co resulted in the formation oxygen-defected CoO_x sites and surface acidic sites, which were beneficial for the adsorption of GVL and the activation of C-O/C=O bonds. The proximity between Cu particles and defective CoO_x facilitated the dissociative adsorption of H₂ on Cu⁰ and the subsequent hydrogen spillover to CoO_x sites, thereby significantly promoted the selective hydrogenation of GVL to 1,4-PeD. In addition, applications of the Cu_0.2Co_0.8Al catalyst to the ring-opening reactions of other lactones (including α-adamyllactone, γ-caprolactone, δ-pentyllactone, and ε-caprolactone) were further investigated. Eventually, high yields (> 93%) of the corresponding diols were attained, demonstrating the excellent catalytic versatility of Cu_0.2Co_0.8Al in selective hydrogenation of lactones. Overall, this work shows high potential of hydrotalcite-derived CuCoAl catalysts for selective hydrogenation of GVL to 1,4-PeD, and provides insights for the design of efficient bimetallic catalysts in lactone hydrogenolysis.

The difference between vitrinite and inertinite in coal has been regarded as the starting point, and the vitrinite and inertinite stripped from a coal sample were conducted by high-temperature (600 °C and 900 °C) and high-pressure (1.0, 1.5, and 2.0 GPa) experiments. The samples' molecular structure was examined with element analysis, Fourier-transform infrared spectroscopy, and X-ray diffraction. The results reveal that pressure has an inhibitory effect on the evolution of molecular structure at 600 °C, and the vitrinite shows a lower molecular structure evolution degree than inertinite. For the two macerals at 900 °C, with increasing pressure, the molecular structure parameters exhibit opposite regularities to those at 600 °C, and the vitrinite shows a higher molecular structure evolution degree than inertinite. The evolution rate of molecular structures caused by pressure in vitrinite remains consistent under different temperature conditions, whereas that in inertinite exhibits jumping changes. There must be a transition interval between 600 °C and 900 °C that can change the pressure from inhibiting coalification to promoting coalification. When the temperature exceeds the transition interval, pressure can accelerate the molecular structure evolution in vitrinite, causing it to catch up with and surpass the evolution degree of inertinite's molecular structure.

Furfural is one of the most prospective platform chemicals derived from biomass. This review summarises the principal factors governing the yield/selectivity of furfural by solvolysis technique, with a particular attention to the conversion of C6 cellulose feedstock. So far, most studies focused on the C5 sugar-rich feedstock, which requires solely dehydration to convert into furfural. In contrast, the conversion of C6 sugars to furfural is more challenging, requiring dehydration and CC bond breakage. Depending on the type of biomass and catalyst, the reaction temperature and residence time have an optimum value of ∼160–180 °C and ∼ 30–120 min respectively in traditional heating mode. The low optimum temperature (∼140 °C) for the microwave-assisted technique and that C5 polymers do not necessarily require longer reaction time than their monomers indicate that microwave irradiation is more efficient in depolymerisation reaction of polymers. Additionally, the organic solvent systems containing <10 wt% water were the most promising. For catalysts, sulphates/sulphonated catalysts showed the highest potential for furfural production, and Zn²⁺, Cu²⁺ and Fe³⁺ are the most promising cationic candidates. Finally, the future perspectives were proposed, including development of novel heterogeneous catalysts and microwave-assisted technique, kinetic study and mechanistic study for the conversion of C6 sugars.

Benzene, mostly produced from fossil fuel sources, is an essential chemical to many modern industries. Alternatively to non-renewable methods currently used, the present work explores using fast pyrolysis biomass-derived bio-oils to furnish this valuable platform molecule. Notably, we report for the first time the impact of different operational parameters on the highly selective continuous catalytic hydrodeoxygenation of guaiacol, a bio-oil model compound, into benzene using a Mo₂C/CNF-based catalyst. The parametric study includes a first evaluation of the effect of the hydrogen pressure (25, 50 and 75 bar), temperature (300, 325 and 350 °C) and weight hourly space velocity (4 and 10 g_org g_cat⁻¹ h⁻¹) on the guaiacol conversion and product distribution, and a subsequent long-term evaluation (30 h on stream) of the catalyst under appropriate processing conditions The experimental results revelated that our Mo₂C/CNF was able to achieve a conversion of 90–98% with a relative amount of benzene in the liquid product up to 81% for at least 30 h without any sign of deactivation at 75 bar of H₂ and 350 °C, which is a landmark achievement in the conversion of bio-oil derived molecules into platform chemicals.

Identification of the underlying cause of carbon loss in fatty acid hydrodeoxygenation (HDO) on the acidic catalyst is very important to understand the reaction mechanism and design high efficiency catalyst for biomass conversion. Herein, HDO reactions of palmitic acid catalyzed by Ni supported on mesoporous Beta (HBeta-M) zeolites with different acidities were investigated. It was found that a significant carbon loss (47.5%) occurred during the entire reaction process on Ni/HBeta-M catalyst with high acid density. This is because the hexadecyl ether intermediate was formed and trapped in the porous structure of the catalyst and interacted with strong acidic sites. On the Ni/HBeta-M-0.5 catalyst with medium acid density, carbon loss occurred in the initial reaction stage because hexadecanol was trapped in the porous catalyst. Investigations further demonstrated that the hexadecyl ether intermediate can also be converted to hexadecanol and hexadecane via hydrogenolysis on Brønsted acid and Ni sites.

Drop-in biofuels can play an important role in the transition from fossil-based fuels to carbon-neutral energy carriers. This work focuses on performance and emission of hydrotreated pyrolysis oil (HPO) for heavy-duty (HD) engines application. The HPO is blended with marine gas oil (MGO) in various mass ratios and tested both in combustion research unit (CRU) and engine facilities. Typical cruise speeds and multiple loads are selected in the heavy-duty engine tests. Both inlet temperature and EGR rate are varied to investigate the effects of control parameters on HPO. The results reveal that HPO present lower reactivity than MGO and diesel under CRU condition. It can function as a drop-in fuel without any modification to the engine and no recalibration was required. Specifically, key combustion phases are noticed to be identical. The engine can run smoothly and safely at 50% blend ratio with 1% reduction on net indicated efficiency (NIE) and 0.002 g/kWh particulate matter emissions (PM). At low load, the NOx emissions decrease to 1 g/kWh at 40% EGR, yet 1% decrease of NIE is shown. While all fuels yield more NOx but less PM emissions as the increase of inlet temperature. Inlet heating does decrease the NIE by 1%.

The co‑carbonization of refined coal tar pitch (RCTP) and brominated industrial methyl naphthalene (BIMNP) employing benzoyl chloride (BC) as a catalyst has been explored to create an isotropic spinnable pitch for carbon fibers with notable tensile strength. BIMNP is derived from industrial methyl naphthalene (IMNP) via photo-bromination assisted by visible light using N-bromosuccinimide (NBS) as a brominating agent. This research investigates the impact of the mass ratio of RCTP and BIMNP on the composition, molecular structure, and thermophysical characteristics of the co‑carbonized pitch. A tentative elucidation of the co‑carbonization mechanism involving RCTP, BIMNP, and BC is presented. Adjusting the NBS-to-IMNP mass ratio leads to the complete conversion of 1-methylnaphthalene (1-MNP) and 2-methylnaphthalene (2-MNP) in IMNP into 1-bromomethylnaphthalene (1-BMNP) and 2-bromomethylnaphthalene (2-BMNP), respectively. The co‑carbonized pitch exhibits enhanced pitch production, increased thermal stability, and improved spinnability compared to pitch synthesized via thermal polycondensation. The resulting carbon fibers experience a rise in tensile strength by 947 MPa and an increase in Young's modulus by 41.3 GPa as BIMNP content varies from 10% to 30%. Using BIMNP as a co‑carbonization agent offers a promising avenue for producing pitch-based carbon fibers meeting automotive industry requirements.