Pressure Pyrolysis Research Articles

High Quality Bio-Oil Production via Catalytic Pyrolysis of Pine Sawdust

The objective of this study was to increase the selectivity of hydrocarbons in bio-oil by changing the degree of closure of the reactor. Using pine sawdust with a particle size of 0.5 to 0.8 mm as the pyrolysis material and HZSM-5 with a SiO2/Al2O3 ratio of 60 as the catalyst, biomass catalytic pyrolysis experiments were carried out in a fixed bed reactor. The bio-oil compositions as a function of the closure time of the reactor and the catalyst-to-biomass weight ratios were investigated. The deactivation of the catalysts was also evaluated. The selectivity for the hydrocarbons obtained in the bio-oil was 18.99% at conditions of 550 °C reaction temperature and 20 wt.% HZSM-5 catalyst usage with no closure time. When the closure time of the fixed bed reactor was 1 h, the selectivity of the hydrocarbons reached 95.28%, and the heating value reached 32.5 MJ/kg; however, the organics yield in the liquid product was only 6.2%. This investigation verified that the quality of the bio-oil could be improved significantly through the closure of the reactor, which could be due to pyrolysis vapors that could be treated by the coupling effect between a high pressure and catalytic pyrolysis.

Role of the interlayer space of montmorillonite in hydrocarbon generation: An experimental study based on high temperature–pressure pyrolysis

The interlayer clay–organic complex is an important clay–organic association in sedimentary environments. However, the effects of organic matter storage in the interlayer space of clay minerals on the thermal degradation of organics and the generation of hydrocarbons have not been investigated. In this study, montmorillonite (Mt) and 12-amoniolauric acid (ALA) were used to prepare an interlayer Mt–ALA complex and a Mt–ALA complex in which Mt and ALA were simply mixed. Pyrolysis experiments on the ALA and Mt–ALA complexes were conducted in a confined gold capsule system at a fixed temperature and pressure of 350°C and 36MPa, respectively. X-ray diffraction, elemental analysis and Fourier transform infrared spectroscopy were used to characterize the Mt–ALA complexes, and automatically controlled gas chromatography along with a pyrolysis furnace was used to detect the volatile components released during pyrolysis. In the absence of Mt, the pyrolysis of ALA yielded only a small amount of C1–5 hydrocarbons and CO2. The amounts of C1–5 hydrocarbons released from the pyrolysis of the interlayer Mt–ALA complex and the mixed Mt–ALA complex are approximately 43 and 5 times greater than the amounts released from ALA alone, respectively. The Brønsted acid sites in the interlayer space of Mt, which arise from the interlayer dissociated water, significantly promote the cracking of hydrocarbons through a carbocation mechanism, the isomerization of normal hydrocarbons and alkene–alkane conversion through hydrogenation, resulting in high i-alkane/n-alkane and alkene/alkane ratios in the pyrolysis products. The Lewis acid sites of Mt are primarily involved in the decarboxylation of ALA during pyrolysis and are responsible for CO2 generation.

Wine industry waste thermal processing for derived fuel properties improvement

The paper presents the results of pyrolysis process applied as pre-treatment sequence for grape marc within energy conversion chain. Experimental campaign for proximate, ultimate and calorimetric characterization of the product was conducted. The product equivalent chemical formula was established – C4H7O3. The atmospheric pressure pyrolysis with external heat source at temperatures between 350 °C–600 °C was studied with respect to process parameters influence on end-products formation, distribution and physical–chemical properties. Based on experiments the product activation energy of 111.5 kJ/mol was determined. The process parameters influence on end-products energy content, pyrolysis energy consumption and global energy efficiency was established. The research focused on maximum net energy content delivered in pyrolysis products as high quality fuel for energy conversion processes. The study revealed that pyrolysis gas alone can ensure the process self-sustenance for the applied temperature range. The optimum treatment temperature with respect to global energy balance was found at 550 °C.

A wide range kinetic modeling study of pyrolysis and oxidation of benzene

The aim of this work is to collect and review the vast amount of experimental data reported in recent years on benzene pyrolysis and oxidation and to analyze them by using and refining a detailed kinetic mechanism, thereby identifying a sensitive and crucial portion of the mechanism itself. Benzene is the first aromatic compound, a relevant intermediate of several combustion processes and also a key precursor to soot formation. The emphasis here is on high pressure pyrolysis experiments, ignition delay times in shock tubes, premixed flames as well as low temperature reactions with recombination and propagation reactions of cyclopentadienyl and phenoxy radicals playing a significant role. This is the first time the same kinetic model of benzene pyrolysis and oxidation has been compared with such a wide collection of experimental measurements.

Exploiting Algae As a Biomass Source to Produce Gasoline Grade Hydrocarbons by High Pressure Pyrolysis

The use of microalgae as a feedstock to produce hydrocarbon fuels using high pressure catalytic pyrolysis was studied. In this study, freeze dried microalgae species Nannochloropsis oculata was studied as the biomass source for py-rolysis in a micro-reactor. Algae sample was characterized by thermo gravimetric analysis (TGA) as well as FTIR analysis. To augment the hydrocarbon fraction, the effects of temperature and pressure were studied by varying the temperature from 500-800 oC in 100 oC increments and pressure 0-150 psi in 50 psi increments. When the sample was heated from 500-800 oC the volatiles were mainly hydrocarbons with small percentage of oxygenated and nitrogenated species. It was found that the gases evolved within 100-500oC were mostly oxygenated, nitrogenated and sulfided species.

Reaction mechanism and kinetics of pressurized pyrolysis of Chinese oil shale in the presence of water

A study of reaction mechanisms and chemical kinetics of pressurized pyrolysis of Chinese Liushuhe oil shale in the presence of water were conducted using an autoclave for simulating and modeling in-situ underground thermal degradation. It was found that the oil shale was first pyrolyzed to form pyrobitumen, shale oil, shale gas and residue, then the pyrobitumen was further pyrolyzed to form more shale oil, shale gas, and residue. It means that there are two consecutive and parallel reactions. With increasing temperature, the pyrobitumen yield, as intermediate, first reached a maximum, then decreased to approximately zero. The kinetics results show that both these reactions are first order. The activation energy of pyrobitumen formation from oil shale is lower than that of shale oil formation from pyrobitumen.

Slow and pressurized co-pyrolysis of coal and agricultural residues

The distribution of products from the slow heating rate pyrolysis of coal, corn residues (cobs and stover), sugarcane bagasse and their blends were investigated by slow pressurized pyrolysis in a packed bed reactor. A factorial experimental design was implemented to establish the relative significance of coal–biomass mix ratio, temperature and pressure on product distribution. Results showed that the yield and composition of tar and other volatile products were mostly influenced by mix ratio, while temperature and pressure had a low to negligible significance under the range of conditions investigated. Analysis of the composition of condensates and gas products obtained showed that there was significant synergy or chemical interactions in the vapor phase during co-pyrolysis of coal and biomass. However, the interactions did not significantly affect the relative distribution of the lumped solid, liquid and gas products obtained from the blends, beyond what would be expected assuming additive behavior from the contributing fuels.

The Physical Properties and Gasification Activities of Pressurized Rapid Pyrolysis Chars from Coal and Petroleum Coke

In the pressurized rapid pyrolysis process, the two kinds of carbonaceous materials (coal and petroleum coke) presented some different pyrolysis behaviors, resulting in some different effects of pyrolysis conditions (thermal history and pyrolysis pressure) on their physical properties (carbon crystalline structure and surface area). The gasification activity of their resultant chars prepared at the ambient pressure was higher than that of their corresponding ones prepared at the pressurized pyrolysis. However, at the pressurized pyrolysis, the effects of pyrolysis pressure on the gasification activity of their resultant chars were obviously discriminated, which was likely to be quite pertinent with that whether the tars were produced or not during the pyrolysis.

The high pressure study of n-propylbenzene pyrolysis

The high pressure and high temperature kinetics of n-propylbenzene pyrolysis were investigated in the High Pressure Single Pulse Shock Tube at University of Illinois at Chicago. Experiments were performed at a nominal pressure of 50atm, with the temperatures ranging from 1027 to 1678K. A variety of stable species ranging from aliphatic hydrocarbons to single ring and polycyclic aromatic hydrocarbons were sampled from the shock tube and analyzed using standard gas chromatographic techniques.A detailed chemical kinetic model was developed to simulate the stable species profiles as obtained from the high pressure pyrolysis experiments. The model provides a satisfactory fit for the consumption of the fuel and the formation of the major aliphatic, monoaromatic and polycylic aromatic hydrocarbons.

Preparation of a novel BN/SiC composite porous structure

A kind of BN/SiC open cell ceramic foams were fabricated from complex co-polymeric precursors of polycarbosilane and tris(methylamino)borane [B(NHCH3)3] using a high pressure pyrolysis foaming technique. The as-fabricated foams exhibit cell sizes ranging from 1 to 5mm with bulk densities varying from 0.44 to 0.73g/cm3, depending on the proportion of the starting materials. Studies on microstructure and properties of the porous material shown that addition of BN into SiC can improve dramatically its oxidation resistance during 800–1100°C and compression strength which was generally about a 5–10 times higher than that of a pure SiC foam.

Structural changes in coal chars after pressurized pyrolysis

The aim of this work was to evaluate the effect of pressure on the structural properties and subsequent reactivity of coal chars. Pyrolysis reactions were carried out in a fixed bed reactor by varying the pressure up to 2.0MPa. Two coal samples with a substantial difference in the swelling index were used for the analysis. Pyrolysis experiments were carried out at 800°C for 30min after heating the sample at a constant rate of 20°C/min and some samples were pyrolyzed at 900°C and 0.1MPa for comparison. Structural analysis of the coal chars was performed using Raman microscopy; this characterization was complemented by scanning electron microscopy analysis, gas adsorption and reactivity towards molecular oxygen in a thermogravimetric equipment. Characteristic Raman bands of coal chars exhibited significant changes from 0.1 to 0.5MPa, after this pressure no significant changes were observed with pressure increments. The pyrolysis pressure showed to have an influence in the ordering of the carbonaceous structures through the deconvoluted Raman spectra.

Thermal conversion of glucose to aromatic hydrocarbons via pressurized secondary pyrolysis

In this study, glucose, a primary building-block of biomass was subjected to secondary pyrolysis in a reactor that was retrofitted subsequent to a primary micro-pyrolysis reactor. It was observed that incorporation of a secondary reactor resulted in producing significant amounts of gasoline range hydrocarbons. The hydrocarbon yields improved further as a result of increasing pyrolysis reactor pressure and temperatures. The temperature of the secondary reactor was varied between 400 and 800°C and pressure between 0 and 150psi. This study indicates that secondary cracking of primary pyrolysis products of biomass oxygenates undergo gas-phase homogenous molecular restructuring. The result of this process is production of substantial amounts of thermodynamically stable gasoline-range hydrocarbons even in the absence of a catalyst.

Deoxygenation of Methanol over ZSM‐5 in a High‐Pressure Catalytic Pyroprobe

AbstractDeoxygenation is a critical step in making hydrocarbon‐rich biofuels from biomass constituents. Although the thermal effects of oxygenate aromatization have been widely reported, the effect of pressure on this critical reaction has not yet been closely investigated, one primary reason being the unavailability of a reactor that can pyrolyze oxygenates, especially those in solid form, under pressurized conditions. Here, the first of a series of studies on how oxygenates behave when catalytically pyrolyzed under elevated pressure and temperature conditions is reported. Methanol, the simplest alcohol, was selected as the candidate to study the chemical phenomena that occur under pressurized catalytic pyrolysis. The reactions were carried out over the shape‐selective catalyst ZSM‐5 (SiO2/Al2O3 = 30) under varying pressure (0 to 2.0684 MPa (300 psi) in 0.3447 MPa (50 psi) increments) and temperature (500 to 800 °C in 50 °C increments) conditions. Benzene, toluene, ethyl benzene, and xylenes (BTEX) were analyzed as the deoxygenated products of the reaction. The results indicate that the reactor pressure significantly affects deoxygenated product composition.

Analysis of Gaseous and Liquid Products from Pressurized Pyrolysis of Flax Straw in a Fixed Bed Reactor

Pyrolysis of flax straw was investigated under a nitrogen atmosphere using a tubular reactor at different pressures, ranging from 10 to 40 psi. The effects of pressure on the pyrolysis yields and the products obtained (gas, liquid, char) have been analyzed. The gaseous products were analyzed by online GC, and the bio-oils were characterized by gas chromatography/mass spectrometry (GC/MS). Scanning electron microscopy (SEM) was used to view the char surfaces in order to characterize the char and validate the presence of porosity. As the pyrolysis pressure increased, the yield of char and liquid decreased while the gas products increased. The gas products were mainly CO, H2, CO2, CH4, and C3’s. The bio-oils were mostly composed of phenolic compounds, carboxylic acids, and furfural. The pH and the density of the bio-oil revealed a moderate increase with increasing pressure. The SEM study confirms the porous nature of the char. Overall, bio-oil production was maximized at 10 psi; however, char and hydrogen pr...

Synthesis of platinum nanoparticles on carbon aerogel by ambient pressure drying method

Platinum nanoparticles were successfully synthesized on porous carbon aerogel with narrow pore size distribution by ambient pressure drying method. Platinum doped carbon aerogels were synthesized by sol–gel polymerization of resorcinol with furfural in non aqueous medium followed by ambient pressure drying and pyrolysis of organic gel. These samples were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and Flow Chemisorption. TEM and XRD results showed that size of platinum nanoparticle varies between 2 and 5 nm depending on platinum loading and pyrolysis temperature. Hydrogen pulsed chemisorption showed 26.5% dispersion of platinum nanoparticles in carbon aerogel.

Pressurized Fast-Pyrolysis Characteristics of Typical Chinese Coals with Different Ranks

The pressurized fast pyrolysis of three typical Chinese coals with different coal ranks (Huolinhe lignite, Shenmu bituminous coal, and Jincheng anthracite) was conducted on a self-made pressurized fixed-bed reactor. The physicochemical characteristics of the chars were studied via scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). In addition, thermogravimetric analysis (TGA) at ambient pressure has been used to study the influence of the residence time, the pyrolysis temperature, and pressure on the gasification reactivity of residual chars. The results show that the change in char yield and reactivity with pressure, at a residence time of 1 min, is different from that at longer residence time. This is related to the changing impacts of the rapid primary release of volatiles and the slower secondary cracking reactions of the evolved tars and the graphitization of the char structure. Furthermore, as the coal rank, pyrolysis pressure, temperatu...

Nonprecious Oxygen Reduction Catalysts Prepared by High Pressure Pyrolysis: Transition Metal Concentration Effects

not Available.

Differences in physical properties and CO 2 gasification reactivity between coal char and petroleum coke

This paper mainly investigated the physical properties and gasification reactivity of coal char and petroleum coke, separately at the high temperature pyrolysis (950–1400 °C) with slow heating rate and pyrolysis pressure of the atmospheric pressure and at the pressurized pyrolysis (the atmospheric pressure to 3 MPa) with rapid heating rate and the pyrolysis temperature of 950 °C. Some significant differences in those between coal chars and petroleum coke were found. The high temperature pyrolysis caused more easily the graphitization of petroleum coke than that of coal char, especially in the higher temperature range. The increasing pyrolysis temperature resulted in the decrease of surface areas of coal char and the increase of surface areas of petroleum coke. As the pyrolysis pressure was elevated from the atmospheric pressure to 3 MPa, surface areas of petroleum coke initially increased and then decreased, while those of coal chars presented an opposite tendency. The increasing pyrolysis temperature was adverse to the gasification activity of coal chars and was favorable for the gasification activity of petroleum coke. Also, the effects of the pyrolysis pressure on the gasification activity of coal char and petroleum coke were significantly different. The gasification activity of petroleum coke was obviously lower than that of coal chars, and even lower than that of the natural graphite.

Staged Catalytic Gasification/Steam Reforming of Pyrolysis Oil

Gasification/steam reforming of pyrolysis oil was studied in a staged reactor concept, which consisted of an inert fluidized bed and a catalytic fixed bed. Methane and C2−C3 free syngas is produced at a single temperature around 800 °C at atmospheric pressure. By lowering the temperature of the fluidized bed (432−500 °C), its function is changed from a gasifier to an evaporator, and in this way the subsequent catalyst bed actually sees vaporized pyrolysis oil compounds (instead of a fuel gas), which it can more readily convert to syngas. However, the temperature of the fixed bed cannot be too low (min 700 °C) to avoid excessive carbon deposition. System calculations show that when pressurized (30 bar) pyrolysis oil gasification/reforming is considered, the catalytic exit bed temperature should be high (900−1000 °C) to reach sufficient enough methane conversion when syngas is the desired product. When only steam is added at elevated pressure, the H2/CO ratio readily increases, which is desired for hydrogen production. For other applications (e.g., Fischer−Tropsch), carbon dioxide probably has to be recycled to keep the H2/CO ratio around 2−3. The lower heating value efficiency of pyrolysis oil gasification/reforming is comparable to the lower end of the reported range of commercial methane steam reforming.

Analysis of Bio-Oil, Biogas, and Biochar from Pressurized Pyrolysis of Wheat Straw Using a Tubular Reactor

The main objective of this work was to examine the influence of pyrolysis pressure on product yield from wheat straw pyrolysis. The experiments were performed in a tubular reactor at different pressures (10, 20, 30, and 40 psi) with a constant flow rate of nitrogen (50 cc/min) at a temperature of 500 °C. During pyrolysis, the products obtained are oil, gas, and char. The maximum oil yield was 37.6%, obtained at high pressure (40 psi). Liquid product was analyzed using gas chromatography/mass spectrometry (GC−MS). The percentage of bio-oil compounds increased as operating pressure increased. The major components present in the bio-oil were phenols, methoxyphenols, and substituted methoxyphenols such as eugenol and vanillin. The gas products were mainly CO, H2, CO2, CH4, C2H4, C2H6, C4H10, and C3’s. Char characteristics were measured using scanning electron microscopy (SEM) and ultimate analysis. Van Krevelen diagram shows that the chars obtained from wheat straw pyrolysis have very less H: C and O: C ratio...