Main Gaseous Products Research Articles

One-Pot Synthesis, Crystal Structure, and Thermal Decomposition Behavior of 1,1ʹ-Diamino-4,4ʹ,5,5ʹ-Tetranitro-2,2ʹ-Biimidazole

ABSTRACT1,1ʹ-Diamino-4,4ʹ,5,5ʹ-tetranitro-2,2ʹ-biimidazole (DATNBI) was synthesized, by employing one-pot facile method, from 4,4ʹ,5,5ʹ-tetranitro-2,2ʹ-biimidazole. The crystal structure was determined by X-ray diffraction for the first time. DATNBI crystallized in monoclinic system P21/c, with a crystal density of 1.934 g cm−3 at 293(2) K and 2.019 g cm−3 at 130(2) K, respectively. Its crystal parameters at 293 K are a = 4.8833(15) Å, b = 6.960(2) Å, c = 6.928(4) Å, α = γ = 90°, β = 93.418(6)°, V = 591.1(3) Ǻ3, Z = 2, μ = 0.178 mm−1, and F(000) = 348. The thermal stability and non-isothermal kinetics of DATNBI were studied by differential scanning calorimeter (DSC) with heating rates of 5, 10, 15, and 20 K min−1. The apparent activation energy (Ea) at the first decomposition peak calculated by Kissinger, Ozawa, and Starink equations were 85.50, 89.67, and 86.10 kJ mol−1, respectively. For the second peak, these were 116.49, 119.82, and 117.45 kJ mol−1, respectively, with individual pre-exponential factors lnA = 18.40 s−1 and lnA = 25.11 s−1. The thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) analysis of thermal decomposition products reveals that the main decomposition gas products are H2O, N2O, CO2, and NO2. Based on the new crystalline densities, the detonation velocity and pressure predicted by EXPLO5 are 9062 m s−1 and 36.4 GPa, respectively.

Thermal analysis of molten ternary lithium-sodium-potassium nitrates

The pre-melting, melting and degradation events of a ternary LiNO3-NaNO3-KNO3 (29.63-13.23-57.14 wt%) salt have been investigated using simultaneous thermal analyzer (STA) for potential use as a heat transfer and storage fluid (HTF). This composition was selected based on the thermochemical calculation using the FactSage 7.0 to find the lowest solid-liquid equilibrium temperature. The melting point obtained from STA (122.8 °C) indicated a good agreement with the theoretical value determined by FactSage (120.8 °C), which is 100 °C less compared to binary NaNO3:KNO3 solar salt. The salt was heated from 50 to 800 °C in 3 atm (argon, air, and O2) at three scanning rates (2.5, 5 and 10 °C/min) to investigate its decomposition limits. At 10 °C/min scanning rate the salt started to degrade rapidly at 545 °C in argon, 571 °C in air and 600 °C in oxygen, respectively. In argon at a higher heating rate (10 °C/min), the salt degradation was delayed by 42 °C. The main gaseous products of decomposition were found to be O2, N2, NO, N2O and NO2. After melting, at higher temperature the evolution of O2 and NO indicated that primary and secondary decomposition reactions are concurrent and overlapping. The heating-cooling rates have low effect on the onset of melting and offset freezing temperatures but, have an effect on peaks height, peaks width, and transition enthalpies. The α/β transition (75 °C peak temperature) during cooling only appeared at the 1 °C/min cooling rate. The ternary salt offers 70 °C greater operating temperature range compared to binary solar salt in argon. At a higher partial pressure of O2, decomposition was delayed by 55 °C (at 10 °C/min), which could be used to increase the power cycle efficiency of solar electricity generation.

Thermal degradation of poly(lactic acid) oligomer: Reaction mechanism and multistep kinetic behavior

This study was aimed to reveal the kinetic and mechanistic features of the thermal degradation of linear poly(lactic acid) oligomer (PLAO) by analyzing the evolved gases and overall rate behavior during mass-loss processes. The thermal degradation reaction involved two partially overlapping mass-loss steps. The first mass-loss step started right after the reactant melted and was accompanied with the release of lactides as the main gaseous products while maintaining the microscopic appearance of molten PLAO. The mass-loss rate behavior was controlled by a diffusion process with an apparent activation energy (Ea) of approximately 90 kJ mol–1, with the diffusional transfer of lactides from the reaction sites to the top surface of the molten PLAO being considered as the rate-limiting step. The second mass-loss step became noticeable at reacting system temperatures above the boiling point of lactides. During this dramatically accelerated mass-loss step, carbon oxides, aldehydes, lactides, and cyclic PLAO with large molecular weights were simultaneously evolved with frequent formation and disappearance of gaseous bubbles in the molten reacting system. In this step, the overall rate behavior was largely influenced by the bubbling phenomena for which the Ea value was determined to be approximately 155 kJ mol–1. The changes in the chemical mechanism and the physico-geometrical reaction behavior midway through the thermal degradation reaction were both illustrated by the change in the molten reacting system in view of degradation-polymerization equilibrium via the boiling points of lactides.

Renewable syngas production from thermal cracking of glycerol over praseodymium-promoted Ni/Al2O3 catalyst

In this study, the kinetics of glycerol pyrolysis over a 3wt%Pr-20wt%Ni/77wt%α-Al2O3 catalyst was investigated. The catalyst was synthesized via wet-impregnation method and was characterized using temperature-programmed calcination (TPC), temperature-programmed reduction (TPR), N2-physisorption, FESEM imaging, X-ray diffraction and CO2-/NH3-temperature-programmed desorption (TPD). The catalytic activity of the as-synthesized 3wt% Pr-Ni/α-Al2O3 catalyst was evaluated in a stainless steel fixed bed reactor at temperatures that ranged from 973K to 1073K and a weight-hourly-space-velocity (WHSV) of 4.5×104mlg−1h−1 under the atmospheric condition. The main gaseous products from catalytic glycerol pyrolysis were H2, CO, CO2 and CH4 (descending ranking) with the highest H2 formation rate and H2 yield of 0.02593molgcat−1s−1 and 29.04%, respectively. The analysis of the kinetic data obtained from the glycerol pyrolysis showed activation energy of 37.36kJmol−1. Based on the mechanistic modeling, it can be deduced that the rate determining step of the glycerol pyrolysis was via a single site associative adsorption with molecular surface reaction as the rate-determining step.

An experimental kinetic study and products research of the reactions of O3 with a series of unsaturated alcohols

The gas-phase reactions of unsaturated alcohols with O3 were investigated in FEP Teflon film chamber at 298 K and 760 torr of atmosphere pressure. The rate constants of the reactions of C6-C8 alkenols with O3 were determined using both the absolute and the relative rate method, and the measured values were (5.96 ± 0.35) × 10−17 cm3 molecule−1 s−1 for (Z)-3-hexen-1-ol, (5.12 ± 0.30) × 10−17 cm3 molecule−1 s−1 for (Z)-3-hepten-1-ol, and (5.66 ± 0.52) × 10−17 cm3 molecule−1 s−1 for (Z)-3-octen-1-ol, respectively. The gas-phase products of these reactions mentioned above were detected using proton-transfer-reaction mass spectrum (PTR-MS). HOCH2CH2CHO, CH2CH2CHO, HCHO and CH3CHO were identified as the main gas products for (Z)-3-hexen-1-ol. HOCH2CH2CHO and CH3(CH2)2CHO dominated the gaseous products for (Z)-3-hepten-1-ol. And for (Z)-3-octen-1-ol, CH3(CH2)3CHO, CH3(CH2)2CHO and HOCH2CH2CHO were the main gaseous products. The SOA yields were monitored at the same time, which were 0.184 ± 0.013, 0.213 ± 0.017, 0.232 ± 0.021 for (Z)-3-hexen-1-ol, (Z)-3-hepten-1-ol and (Z)-3-octen-1-ol, respectively. The possible reaction mechanisms were proposed and discussed. The kinetic data presented here has been used to estimate their atmosphere lifetimes and the reaction reactivity. The atmosphere implication of these reactions has also been discussed.

Synthesis, thermal study and some properties of N2O4\u2014donor Schiff base and its Mn(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes

The new hexadentate N2O4 Schiff base ligand from condensation of 2,4-hydroxybenzophenone and 1,3-propanediamine has been prepared in methanol and ethanol solutions. The Schiff base synthesized from EtOH contains half molecule of amine per one molecule of ligand in its structure. The complexes were synthesized from the direct reaction of this ligand and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) acetates. The Schiff base and its complexes were characterized by elemental analysis, X-ray crystallographic techniques, spectroscopic (UV–Vis, IR) and thermal (TG, TG-FTIR) methods, molar conductance and magnetic measurements. The complexes, except for Ni(II) compound, similar to the Schiff base are amorphous solids. The Ni(II) complex crystallizes in the monoclinic space group P21/c. The N2O2 coordination geometry around nickel(II) is slightly tetrahedrally distorted square planar. Variable temperature magnetic studies of the paramagnetic complexes show the existence of weak antiferromagnetic [for complexes of manganese(III) and cobalt(II)] and weak ferromagnetic [for copper(II)] interactions. The complexes are stable at ambient temperature. After heating at first they lose solvent molecules (water or methanol), and after that organic part undergoes defragmentation and combustion. Based on the obtained data from the TG-FTIR analysis, the main gaseous products resulting from thermal degradation in nitrogen atmosphere are CO2, CO, NH3, acetic acid, methane, C6H6, C6H5CN and C6H5CH3.

Characterization of Ag-promoted Ni/SiO2 Catalysts for Syngas Production via Carbon Dioxide (CO2) Dry Reforming of Glycerol

The carbon dioxide (CO2) dry reforming of glycerol for syngas production is one of the promising ways to benefit the oversupply crisis of glycerol worldwide. It is an attractive process as it converts carbon dioxide, a greenhouse gas into a synthesis gas and simultaneously removed from the carbon biosphere cycle. In this study, the glycerol dry reforming was carried out using Silver (Ag) promoted Nickel (Ni) based catalysts supported on silicon oxide (SiO2) i.e. Ag-Ni/SiO2. The catalysts were prepared through wet impregnation method and characterized by using Brunauer-Emmett-Teller (BET) surface area, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Thermo Gravimetric (TGA) analysis. The experiment was conducted in a tubular reactor which condition fixed at 973 K and CO2:glycerol molar ratio of 1, under atmospheric pressure. It was found that the main gaseous products are H₂, CO and CH4 with H₂:CO molar ratio < 1.0. From the reaction study, Ag(5)-Ni/SiO2 results in highest glycerol conversion and hydrogen yield, accounted for 32.6% and 27.4%, respectively.

Study on rapid pyrolysis and in-situ char gasification characteristics of coal and petroleum coke

Rapid pyrolysis characteristics of three different rank coals and two petroleum cokes were investigated using a drop tube furnace. Moreover, gasification characteristics of char samples were studied in an in-situ heating stage. The results showed that H2 and CO were the main gaseous pyrolysis products of coal samples. The relative content of H2 and CO increased with increasing pyrolysis temperature. The volume fraction of H2 in syngas increased with increasing coal rank, whereas that of CO showed the contrary trend. Anthracite and petroleum cokes (Petcoke 1 and Petcoke 2) exhibited a great similarity in gas release characteristics. There was a maximum value for the specific surface area and graphitization degree of char samples with increasing pyrolysis temperature. The results of in-situ heating stage experiments indicated that the most of char particles reacted with CO2 in the shrinking particle mode at the initial stage. Char samples of petcokes and anthracite were similar in slow consumption of particle skeleton during gasification. Interestingly, petcokes demonstrated particle migration, residual agglomeration, and rapid consumption at the later reaction stage. The variation trend of the area shrinkage ratio of char samples was well verified by the TGA results.

Hydrothermal gasification of different agricultural wastes in supercritical water media for hydrogen production: a comparative study

Conversion of different agricultural residues including almond shell, walnut shell, barley straw, canola stalk, rice straw and wheat straw to hydrogen-rich gas was performed via gasification in supercritical water media in a determined condition. Elemental characterization was performed using CHNSO analyzer. Besides, cellulose and lignin contents in biomass structure were determined according to TAPPI test methods T264cm-97 and T222om-02, respectively. The correlations between the yields of the product gas components with C/H/O ratio in the initial forms of used feedstocks were investigated. In addition, the relation between the components of biomass structure with the yields of main gaseous products was also studied for each feedstock. The maximum hydrogen yield of 8.38 mmol/g was observed for barley straw which has the highest H percentage of 6.5 wt%. Canola stalk with the highest C/H ratio showed the highest total gas yield of 25.3 mmol/g. Canola stalk with highest amount of cellulose and hemicellulose of 67.42 % had the highest CGE of 45 % and barley straw had the highest HGE of 20 %. Higher C/H value and lower oxygen percentage in the initial form of feedstocks resulted in higher total gas and CO2 yields and lower hydrogen yields. Lignin content in the initial form of the feedstocks was inversely proportional with total gas yields whereas cellulose content showed a straight relation with the total gas yield.

Production of H2 in the photocatalytic reactions of ethane on TiO2-supported noble metals

The effect of illumination on the adsorption and reaction of ethane was investigated on TiO2 and TiO2-supported Pt metals. IR studies showed that new absorption bands developed as a result of illumination of the catalysts. The photocatalytic decomposition of ethane was very limited on pure TiO2: the conversion was only ∼4% at 300 K in 210 min. Deposition of Pt metals onto TiO2 markedly enhanced the rate of photo-induced decomposition of C2H6. Highest conversion of C2H6, 23.5%, was measured over Pt/TiO2 and the turnover frequency was also the highest on this catalyst. Addition of CO2 to ethane exerted no influence on the photocatalysis of ethane. Surprisingly, the main gaseous product of the photocatalytic reaction is H2 with a small amount of CH4. Ethylene was not detected even in traces, indicating the complete degradation of C2H6 to H2 and carbon containing deposit. Temperature programmed reduction (TPR) revealed that the carbonaceous deposit on the catalysts is very stable. On Rh/TiO2 it reacted with H2 to give CH4 (Tp = 453 and 604 K), C2H6 and C3H8 (Tp = 602 K). Similar values were found on Pt/TiO2. The promoting effect of metals was explained by a better separation of charge carriers induced by illumination and by the enhanced electronic interaction between metals and TiO2.

Crude bio-glycerol aqueous phase reforming and hydrogenolysis over commercial SiO2[sbnd]Al2O3 nickel catalyst

In the present work, an one-pot Aqueous Phase Reforming (APR) and Aqueous Phase Hydrogenolysis (APH) of crude glycerol in a batch reactor containing commercial SiO2Al2O3 supported 65%Ni catalyst is performed. The effect of: i) the glycerol’s impurities, ii) the operating temperature (200–240 °C) and iii) the crude glycerol concentration (10–40 wt%) is investigated.The main gaseous products are H2, CH4 and CO2, while the main liquid products are propylene glycol (PG), ethylene glycol (EG), ethanol and acetol. The selectivities of the gaseous and liquid products are not strongly affected by the addition of low concentration impurities of methanol and sodium chloride. Glycerol’s conversion increases as temperature and glycerol’s concentration increases. Total conversion for both pure and crude glycerol is >90%. The yield of the most useful liquid product (propylene glycol) is reaching up to 30% for a 40 wt% of crude glycerol solution at T = 240 °C and 4 h of reaction time.

Synthesis, characterization and catalytic potential of MgNiO2 nanoparticles obtained from a novel [MgNi(opba)]n·9nH2O chain

We describe herein the synthesis of MgNiO2 nanoparticles employing a new one-dimensional system [MgNi(opba)]n·9nH2O, with opba standing for ortho-phenylenebis(oxamato), as precursor. The MgNiO2 nanoparticles could be obtained after heat-treatment at 800°C for 5h under air atmosphere, which was responsible for the elimination of water and organic precursor material leading the formation of nanoparticles with average size of 40±9nm. To this end, we first described the synthesis of [MgNi(opba)]n·9nH2O chain, which was obtained using a pre-synthetized Na2[Ni(opba)]·5H2O and Mg2+ (molar ratio of 1:1) in aqueous media and then this chain was calcined to produce the desired MgNiO2 nanoparticles. The obtained MgNiO2 nanoparticles showed good catalytic performance towards ethanol decomposition achieving 100% of substrate conversion and producing acetaldehyde (56.8%) and hydrogen (24.8%) as the main gaseous products. Also, carbon based structures of great interest for technological applications, carbon nanotubes and onions were formed as valuable byproducts. Thus, we believe that our reported results may inspire the synthesis of catalysts with improved performances for applications in other gas-phase transformations.

Pyrolysis products from industrial waste biomass based on a neural network model

Pyrolysis of pine sawdust, a typical industrial biomass waste, was studied. The effects of operating temperature, biomass particle size, and space velocity on the products of biomass pyrolysis were investigated. A three-layer artificial neural network (ANN) model was developed and trained to simulate and predict the selectivity and yield of gas products. Good agreement was achieved between the experimental and simulated results. The major gas products of biomass pyrolysis are CO, CO2, H2, and CH4. The ANN model showed that the major gas products depended mainly on the temperature, and the total selectivity of CO, CO2, H2, and CH4 increased from 2.91% at 300°C to 34.31% at 900°C. The selectivity of main gas products increased with increasing space velocity. When the space velocity increased from 45min−1 to 85min−1, the selectivity of major gas products increased from 29.12% to 34.03%. Within the sample particle size range from 0.1 to 1.7mm, there was no significant difference in the selectivity of major gas products. The pyrolysis temperature also influenced the composition of the tar in the biomass pyrolysis product. In the temperature range investigated, the benzene composition was favored at lower temperatures, such as 400°C, however, the light-weight PAHs were preferably generated at higher temperatures above 600°C.

Two-stage hydrogasification of different rank coals with a focus on relationships between yields of products and coal properties or structures

The pressurized hydrogasification of different rank coals was carried out using a laboratory two-stage reactor to investigate the influences of volatile matter hydrocracking on the formations of gaseous products (CO2, CO, CH4 and C2–C3) and liquid products (water and light aromatics). Experiments were conducted by way of comparison under the N2 atmosphere. Fourier transform infrared spectroscopy (FTIR), solid state 13C nuclear magnetic resonance technique (13C NMR) and chemical titration analysis were used to semi-quantitatively or quantitatively determine the main functional groups in the coals. It was found that through the hydrocracking at 700°C, the summed yields of CH4 and C2H6 from two lignite coals reached as high as 21.2–22.9% (daf. coal), higher than those even from two subbituminous coals. This result was associated with the abundance of longer alkyl groups in two lignite coals. Two lignite coals were the most enriched with carboxyl groups, which was proved to be the principal precursor of CO2. The hydrocracking at 700°C allowed a distinct part of CO2 to convert into CO by the reversal gas water shift reaction, while the changes in the yields of H2O were indistinct. The hydrocracking at 700°C was also favorable for the production of BTX (benzene, toluene and xylene) and naphthalene. The simple linear regression was used to assess the correlations of the yields of main gaseous products (CH4, C2H6, CO2 and CO) and liquid products (H2O and BTX) obtained under varying conditions to some relevant coal properties such as volatile matter content and total oxygen content as well as to some structural parameters such as aliphatic ratio and carboxyl group content.

Kinetics examination of pressurised steam gasification of beech wood

In Poland, among all renewable energy sources, share of biomass in electricity production is the largest. Great potential in biomass utilization involves use of gasification technology. The course of biomass gasification process in steam atmosphere is the subject of numerous scientific studies. The aim of this study was kinetics examination of pressurized beech wood waste gasification, that can be successfully used in industrial gasification. Measurements were carried out on a unique laboratory installation, that allows kinetics examination of solid fuels gasification with steam at wide range of pressures, via using thermovolumetric method. Formation rates of main gaseous products were determined, moreover, composition of post-reaction gas, as well as biomass conversion degree depending on the temperature were specified. Kinetic parameters of gasification were calculated and series of kinetic models were used to their designation ie Isoconvesional method, Integrated Core Model (ICM), Grain Model (GM) and Random Pore Model (RPM).

Corncob to value‐added chemical transformation by metal/beta zeolite and metal/mesoporous SBA‐15 catalytic pyrolysis

AbstractBACKGROUNDAlthough the pyrolysis of biomass has been investigated by many researchers, there are no data available regarding conversion to value added ester compounds from catalytic corncob pyrolysis at low temperature. In this present research thermal and catalytic cracking of residue corncob was performed at 250 to 600 °C under N2. The performance of two acidic porous catalysts, metal‐beta zeolite and mesoporous SBA‐15, with different metal (Al, Pd and Ni) loadings, were compared with the non‐catalytic reaction.RESULTSThe cracking products were classified into gases, liquid and char. Methane, C5+ and CO2 were the main gas products, while light ester derivatives were the main components in the liquid fraction and these can be important intermediate chemicals. The phenolic compounds were obtained when using low thermal pyrolysis. A reaction temperature of 300 °C with the Al‐SBA‐15 catalyst at a SiO2/Al2O3 mole ratio of 20 was found to be optimal in terms of producing the highest biomass conversion with a high proportion of light esters.CONCLUSIONThe Al‐SBA‐15 (20) catalyst was selective towards producing the light ester 2‐methoxy phenyl acetate (59.4%), which is an important intermediate chemical for production of sweet fruity aromas in the food industry. © 2015 Society of Chemical Industry

A new approach to the non-oxidative conversion of gaseous alkanes in a barrier discharge and features of the reaction mechanism

A new approach to the non-oxidative conversion of C1–C4 alkanes into gaseous and liquid products in a barrier discharge is proposed. It consists in inhibiting the formation of deposits on the reactor electrode surfaces due to the addition of distilled water into the flow of hydrocarbon gases. The energy consumption on hydrocarbon conversion decreases from methane to n-butane from ~46 to 35 eV molecule−1. The main gaseous products of the conversion of light alkanes are hydrogen and C2–C4 hydrocarbons. The liquid reaction products contain C5+ alkanes with a predominantly isomeric structure. The results of modeling the kinetics of chemical reactions show that an increase in the molecular weight of the reaction products is mainly due to processes involving CH2 radical and the recombination of alkyl radicals.

Product analysis during the thermo-oxidation of amorphous deuterated hydrocarbon films with NO2

The excellent thermo-oxidation properties of NO2 have been previously reported, pointing to fast carbon co-deposits removal even at temperatures as low as 200 °C. On the other hand, CO, CO2 and water have been found as the main gas products in oxidation by O2, but in NO2 they have not been confirmed. To make a more accurate assessment, the use of in-situ deposited deuterated hydrocarbon films—to be able to distinguish products from ambient, protonated ones—in a fully-baked chamber have been used in the present work, mainly aimed at detecting heavy (deuterated) water among the reaction products. Other products from hydrogen isotopes could not be identified, but their production would be much lower than water. The ratio of the total deuterium to carbon products detected is lower by an order of magnitude than the D/C ratio of the film (0.04–0.07 to 0.4), probably associated to the difficulties of measuring water in a vacuum system, and the relatively large quantity of background water found. Furthermore, post-oxidation of CO to CO2 has been found for NO2 at any studied temperature, while for O2 a faster post-oxidation which only occurs at T > 275 °C was found. Finally, the implications of the water production in the use of thermo-oxidation in actual and future nuclear fusion devices are also addressed.

Glycerol steam reforming over Ni–Fe–Ce/Al2O3 catalyst for hydrogen production

In this study, we focused on the catalytic activity, stability, and kinetics of glycerol steam reforming (GSR) for the hydrogen production over Ni–Fe–Ce/Al2O3 catalyst. The GSR was investigated in a quartz fixed-bed reactor with an internal diameter of 6 mm under atmospheric pressure, 18.44–44.56 g h/mol weight of catalyst per molar flow rate of glycerol at the inlet (W cat/F AO ratio), 20 wt% glycerol solution concentration, and the temperature range 450–550 °C. Ni–Fe–Ce/Al2O3 catalyst was characterized by N2 physisorption [Brunauer–Emmett–Teller (BET) method], X-ray spectroscopy, temperature-programmed reduction with H2, temperature-programmed desorption of adsorbed CO2 (CO2-TPD), scanning electron microscopy, and thermogravimetric analysis. H2, CO2, CO and CH4 were the main gaseous products with the H2:CO2 ratio at roughly 2.00. The increase in the temperature and W cat/F AO ratio caused the expected increase in the glycerol conversion and H2 yield. All the kinetic parameters for the GSR were obtained in the kinetically controlled reaction regime. The experimental data using the power-law method indicate that the reaction order with respect to glycerol and the activation energy were 0.06 and 32.9 kJ/mol, respectively.

Hydrogenolysis of glycerol to propylene glycol by in situ produced hydrogen from aqueous phase reforming of glycerol over SiO2–Al2O3 supported nickel catalyst

In the present work, the reactions of glycerol's aqueous phase reforming (APR) and Aqueous Phase Hydrogenolysis (APH) in a batch reactor containing SiO2–Al2O3 supported 65% Ni catalyst are performed. The effect of: i) the reaction time (30–240min), ii) the operating temperature (200–240°C), iii) the glycerol concentration (1 or 10wt.%), iv) the catalyst weight (0.5–10g) and v) the gas to liquid phase volume ratio (1.4 or 5ml/ml) on: a) the gaseous and liquid product selectivities and b) the glycerol's conversion is investigated. The main gaseous products are found to be H2, CH4 and CO2, while the main liquid products are found to be propylene glycol (PG), ethylene glycol (EG), ethanol and acetol. Glycerol's conversion increases with the reaction evolution and the increase of the temperature, reaching a plateau. It is found that hydrogen yield is maximized at short reaction times, low glycerol concentrations and increased gas to liquid phase volume ratios, reaching up to 23.5%. On the contrary, the PG yield is favored under the inverse conditions, reaching up to 22%. The higher conversion to gaseous products is found to be ~73.6% and the higher conversion to liquid products ~35.6%. It is also found that, the increased catalyst concentration favors the C–C bond cleavage and the formation of ethylene glycol, ethanol and CH4.