•Hydrocracking of VGO studied in a batch reactor for different NiMoS and zeolite loadings.•Products distributions analyzed using two dimensional chromatography.•Overall activity in hydrocracking is ...determined by zeolite loading.•Selectivity to middle distillate improves with the increase of metal to zeolite ratio.
A new approach has been developed to characterize bifunctional catalysts in a complex matrix of hydrotreated vacuum gas oil using a batch reactor test. Triphasic reactions were carried out in a reactor equipped with a stationary basket, hydrogen injection and products sampling systems. Bifunctional catalysts containing different relative amounts of alumina-supported NiMo sulfide and zeolite were tested at 400°C under 120 bars over different reaction times. The repeatability of the test conditions was validated and the lack of mass transfer limitations at phase interfaces was confirmed. Gas and liquid samples were analyzed by one and two-dimensional gas chromatography (GC×GC) respectively to obtain quantitative distributions of linear and branched paraffins, naphthenes and aromatics. The details of the products distribution provided by chromatography were explained using mechanisms of bifunctional catalysis. It has been established that the limiting step defining the total conversion is the scission of the hydrocarbon chains on acid sites of the zeolite. The increase of the molybdenum to zeolite ratio provided an improvement of middle distillate selectivity.
A vacuum ultraviolet absorbance detector features the addition of the make‐up gas whose purpose is to decrease the diffusion of analytes in the flow cell. It has been previously demonstrated that the ...vacuum ultraviolet detector VGA 100 is a concentration‐sensitive detector for which the signal area is inversely proportional to the total flow in the flow cell. In this work, the signal behavior in the new generation vacuum ultraviolet detector, which features changed configuration for the introduction of make‐up gas, was explored. Contrary to previous instruments, a non‐linear relationship between the detector signal area and the inverse of the total flow in the flow cell (carrier gas flow + make‐up gas flow) was observed. To explain these observations, we have investigated the behavior of the detector in combination with one‐dimensional and two‐dimensional gas chromatography. Based on the results obtained, it was concluded that in these next‐generation instruments, flow in the flow cell cannot be regarded as a simple sum of the gas chromatography column flow and the total make‐up flow. After making modifications to the estimation of the total effective flow in the flow cell, a linear relationship between the signal area and the inverse of the flow in the flow cell was recovered.
The hydrothermal liquefaction of
Spirulina
sp. microalgae (
i.e.
cyanobacteria) byproducts was investigated for the production of road binders from renewable sources. In the 220-300 °C temperature ...range, a water-insoluble viscous material was obtained in a
ca.
50% yield, which consisted of an oily fatty acid-based fraction mixed with organic and inorganic solid residues (
ca.
20%). More interestingly, this material exhibited viscoelastic properties similar to elastomer-containing bitumen, when operating the hydrothermal liquefaction between 240 and 260 °C. This is the first example of a bio-sourced product showing such properties. At higher temperature, fragmentation of species of high molecular weight occurred, resulting in less viscous materials that were no more thermorheologically simple. The reactor filling ratio was also allowed to vary (
i.e.
30%
versus
60%), showing very little influence in terms of yield and viscoelastic properties of the resulting bio-binders.
HTL of
Spirulina
sp. byproducts was investigated for the production of road binders.
The molecular-level structuration of two full photosystems into conjugated porous organic polymers is reported. The strategy of heterogenization gives rise to photosystems which are still fully ...active after 4 days of continuous illumination. Those materials catalyze the carbon dioxide photoreduction driven by visible light to produce up to three grams of formate per gram of catalyst. The covalent tethering of the two active sites into a single framework is shown to play a key role in the visible light activation of the catalyst. The unprecedented long-term efficiency arises from an optimal photoinduced electron transfer from the light harvesting moiety to the catalytic site as anticipated by quantum mechanical calculations and evidenced by in situ ultrafast time-resolved spectroscopy.
•Ex-situ catalytic fast pyrolysis reactor was successfully implemented at laboratory scale.•Pyrolytic vapors conversion was improved in presence of an acidic catalyst.•Quantification of the monomers ...in the liquid phase by GCxGC was achieved.•Ni/HMFI-90 catalyst showed higher bio-oil deoxygenation especially with additional 1% H2.
Catalytic fast pyrolysis (CFP) of beech wood chips was undertaken in a laboratory-scale fixed bed reactor equipped with a biomass semi-continuous dispenser. During pyrolysis, chars are retained on a quartz frit and the pyrolytic vapors are entrained through a fixed-bed catalyst to be converted. Several acidic catalysts such as zeolites H-Beta, zeolite HMFI and 5% Ni supported on HMFI were screened in this equipment. The Ni/HMFI catalyst was also tested in the presence of 1 vol.% of hydrogen in the feed stream. Mass and carbon balances were carefully checked and the gas, liquids and solids fractions were analyzed in-depth to evaluate the impact of the catalyst compared to thermal conversion. In the presence of a catalyst, with a low catalyst-to-biomass ratio of 0.1, a lower amount of bio-oil was formed but it contained less oxygen. The bio-oils were characterized by bi-dimensional GC (GCxGC) coupled with MS and FID detectors. The amount of gaseous products also increased in the presence of all catalysts. In addition of the deoxygenation, gel-permeation chromatography (GPC) showed a decrease of the highest molecular masses in the bio-oil after catalytic treatment, which confirms the conversion of some oligomers. The presence of Ni enhanced the deoxygenation reactions while the addition of H2 is also beneficial to the bio-oil composition.
•Heavy oil hydroconversion was studied in a continuous unit with a dispersed catalyst.•Hydrodynamic behavior was studied in a cold mock-up.•Once-through and recycle mode operations were compared.
A ...continuous micro-pilot unit has been designed to convert petroleum residues with dispersed catalysts. Once-through and recycling modes can be operated. Several operating conditions (residence times and temperatures) have been investigated using the molybdenum naphthenate as catalyst precursor (600ppm). The micro-pilot hydrodynamics has been characterized via a cold mockup by Residence Time Distribution. Whatever the mode used, the conversion, product yields and average molecular weights depends only on residence time and temperature.
Ferrospinels with different metals—Fe, Ni, Co, and Cu—were investigated as oxygen ion and electron carrier materials for the chemical-loop reforming of ethanol, aimed at the production of H
2
with ...intrinsic separation from CO and CO
2
. The materials used showed different behaviours both during the first step of the loop—the reduction of the annealed spinel with ethanol—and the second step—the re-oxidation with steam—as well as with the increasing cycle number. The differences shown were rationalised in terms of redox behaviour, carbon residue accumulation during the cycle, and ability to restore the starting spinel structure during cycling. Mixed ferrospinels showed enhanced reducibility when compared to magnetite; however, since coke accumulation was unavoidable, the best-performing material amongst the materials tested was Co ferrite, which underwent the greatest reduction and was able to maintain it throughout repeated cycles.
Comprehensive two-dimensional gas chromatography (GC times GC) is a technique which is rapidly gaining importance for the analysis of complex samples, especially within petrochemical matrixes. Until ...recently GC times GC has been a technique used within analytical laboratories to characterize complex multi-component mixtures such as fuels, perfumes and organic aerosol extracts, which are difficult to analyze using conventional GC or GC-MS techniques. In the present study we will illustrate how GC times GC-qMS can be used as an effective tool to accurately monitor the conversion of a Straight Run Gas Oil (SRGO) on a Cobalt Molybdenum (CoMo) supported on an alumina sulfide catalyst. A SRGO was hydrotreated at various temperatures and liquid hourly space velocities (LHSV). The products were analyzed and attention was paid to the transformation of sulfur and aromatic compounds. Quantitative analyses using GC times GC-qMS were performed and compared to the "Simulated Distillation" and total sulfur analysis illustrating that this technique can provide a comprehensive view of the entire matrix, family of products and their distribution as well as single molecule evolution upon catalytic conversion.
Abstract The molecular‐level structuration of two full photosystems into conjugated porous organic polymers is reported. The strategy of heterogenization gives rise to photosystems which are still ...fully active after 4 days of continuous illumination. Those materials catalyze the carbon dioxide photoreduction driven by visible light to produce up to three grams of formate per gram of catalyst. The covalent tethering of the two active sites into a single framework is shown to play a key role in the visible light activation of the catalyst. The unprecedented long‐term efficiency arises from an optimal photoinduced electron transfer from the light harvesting moiety to the catalytic site as anticipated by quantum mechanical calculations and evidenced by in situ ultrafast time‐resolved spectroscopy.
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