Stainless Steel Tubular Reactor Research Articles

Catalytic Performance of Bimetallic Cobalt–Nickel/Graphene Oxide for Carbon Dioxide Reforming of Methane

The design of economical and robust catalysts is a substantial challenge for the dry reforming of methane (DRM). Monometallic nickel-based catalysts used for DRM reactions had comparable activity to noble metals. However, they turned out to be less stable during the reactions. As a continuation of the interest in synthesizing catalysts for DRM, this paper evaluates the catalytic performance of bimetallic Co–Ni catalysts regarding their synergy effect, with graphene oxide (GO) as support for the first time. The synthesized bimetallic catalysts prepared via the wet-impregnation method were characterized using N2 physisorption analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The catalytic test was performed in a stainless-steel tubular reactor in atmospheric conditions with a reaction temperature of 800 °C, time-on-stream (TOS) of 300 min and CH4: CO2 being fed with a ratio of 1:1. The bimetallic 10 wt%Co–10 wt%Ni/GO and 20 wt%Co–10 wt%Ni/GO catalysts had a similar BET specific surface area in N2 physisorption analysis. The XRD pattern displayed a homogeneous distribution of the Co and Ni on the GO support, which was further validated through SEM–EDX. The conversion of CO2, CH4, and H2 yield decreased with reaction time due to the massive occurrence of side reactions. High conversions for CO2 and CH4 were 94.26% and 95.24%, respectively, attained by the bimetallic 20 wt%Co–10 wt%Ni/GO catalyst after 300 min TOS, meaning it displayed the best performance in terms of activity among all the tested catalysts.

Experimental Characterization of a Novel Foam Burner Design for the Low-Excess-Enthalpy Combustion of Very Lean Syngas Mixtures

In the present work, a novel foam burner design is proposed and experimentally evaluated for operation with highly diluted syngas mixtures. The lab-scale burner consists of a purpose-built, square-shaped, high-temperature-grade stainless steel tubular reactor filled with square-sectioned siliconized silico carbide (SiSiC) foams. The assembly was installed in an electrical furnace. Spatially resolved temperature measurements were obtained along the reactor axis, while simultaneous measurements of CO, CO2, H2, O2, and N2 were taken at the burner exit and the water levels were recorded upstream and downstream of the reactor. The results clearly show that flames can be stabilized along the reactor for a range of foam characteristics and operating conditions. Hydrogen conversion efficiencies in excess of 98%, and overall thermal efficiencies close to 95% were achieved for the selected operating conditions. Overall, the denser 10 ppi foam demonstrated superior combustion characteristics in terms of stability, lower enthalpy rises, and a wider operating range at the expense of a very modest pressure drop penalty. Finally, scanning electron microscopy, coupled with energy dispersion spectroscopy (SEM/EDS) and Raman spectroscopy analyses, was used to determine the morphological and compositional characteristics of the pristine and aged foams. After more than 100 h of operation, no significant performance degradation was observed, even though the burner design was subjected to considerable thermal stress.

On the mechanism of initiation steam cracking of C6 hydrocarbons by hyperbranched poly(amidoamine) (PAMAM) initiator

Initiators with low bond dissociation energy can initiate the cracking of hydrocarbons, but the initiation effect on hydrocarbons with different molecule structures remains ambiguous. In this study, the steam cracking of three C6 hydrocarbons, namely n-hexane, iso-hexane and methyl-cyclopentane (MCP), initiated by hyperbranched poly(amidoamine) (PAMAM) were investigated experimentally in a stainless-steel tubular reactor, and the detailed kinetic reaction models and reaction process simulations were conducted by Reaction Mechanism Generator and Chemkin-pro software packages. The results confirm that the addition of PAMAM can significantly promote the cracking conversion and reduce the initial cracking temperature of hydrocarbons because the decomposition of PAMAM at relatively low temperature produces high concentration of active NH2 and CH3 radicals, which significantly increases the rate of hydrogen abstraction. Importantly, the promotion efficiency of the initiator can be highly dependent on the cracking behaviour of hydrocarbons. The initiator will show higher promotion efficiency for hydrocarbon that is more prone to undergo sustained hydrogen abstraction after initiation. Therefore, the promotion efficiency of PAMAM follows the order of n-hexane > iso-hexane > MCP. This study is helpful for a better understanding of the initiation mechanism and will guide the design and screening of effective initiators for naphtha with different compositions.

Identifying Key Descriptors for the Single-Atom Catalyzed CO Oxidation

Identifying Key Descriptors for the Single-Atom Catalyzed CO Oxidation

Biofuels and biochars production from agricultural biomass wastes by thermochemical conversion technologies: Thermogravimetric analysis and pyrolysis studies

Abstract In this paper, thermal degradation (TGA) and pyrolysis studies of sunflower shell biomass (SSB), eucalyptus biomass (EB), wheat straw biomass (WSB), and peanut shell biomass (PSB) were carried out using the thermogravimetric analysis and stainless steel tubular reactor. Thermal degradation of all biomass wastes was examined at a heating rate of 10 °C/min in nitrogen atmosphere between 20 and 800 °C. Experiments of pyrolysis were carried out in a tubular reactor from 300 to 700 °C with a heating rate of 10 °C/min, a particle size of 0.1–0.3 mm and nitrogen flow rate of 100 mL.min−1, which the aim to study how temperature affects liquid, solid, and gas products. The results of this work showed that three stages have been identified in the thermal decomposition of SSB, EB, WSB, and PSB wastes. The first stage occurred at 120–158 °C, the second stage, which corresponds to hemicellulose and cellulose's degradation, occurred in temperatures range from 139 to 480 °C for hemicellulose, and from 233 to 412 °C for cellulose, while the third stage occurred at 534–720 °C. It was concluded that temperature has a significant effect on product yields. The maximum of bio-oil yields of 37.55, 30.5, 46.96, and 50.05 wt% for WSB, PSB, SSB, and EB, were obtained at pyrolysis temperature of 500 °C (SSB, PSB, and WSB) and 550 °C (EB). Raw biomass, solid and liquid products obtained were characterized by elemental analysis, Fourier transformed infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), and x-ray diffraction (XRD). The analysis of solid and liquid products showed that bio-oils and bio-chars from agricultural biomass wastes could be prospective sources of renewable fuels production and value added chemical products.

Investigation of palm fibre pyrolysis over acidic catalyst for bio-fuel production

This research aimed to evaluate the pyrolysis reaction for bio-fuel production from palm fibre. A preliminary step to investigate the effect of different type of heterogeneous catalyst revealed three different catalysts: zeolite type (H-Beta), tungsten–zirconia (WO3/ZrO2) and modified alumina (KOH/Al3O2). An increase in temperature was found to have a positive impact on the production of bio-fuel. Bio-fuel synthesis performed in a stainless steel tubular reactor was found to optimized at 650 °C using WO3/ZrO2 as a catalyst resulting in 40.5% bio-fuel, 7.1% bio-char and 14.3% gas. Formation of gas product is due to the presence of strong acid sites on the surface of WO3/ZrO2 promoting cracking reactions. H-Beta catalyst produced the largest about of bio-char which is also due to strong acid sites and narrow catalytic pore structure which caused rapid deposit of coke and then formation of bio-char. Pyrolysis of palm fibre over KOH/Al2O3 catalyst produced the least amount of bio-fuel, but contain the largest composition of phenolic compounds. These compounds are the transformed from lignin content in palm fibre on alkaline sites of the KOH/Al2O3 catalyst. A larger scale production facility was designed to produce larger amount of bio-fuel for the engine performance test. The biofuel blended gasoline (10% biofuel) was tested in an eight-cylinder spark–ignition engine. Engine performance testing revealed that the brake power and torque generated from combustion of bio-fuel blended oil was lower than conventional gasoline. The brake specific fuel consumption of bio-fuel blended was slightly higher than conventional gasoline.

Torrefaction of agro-wastes (palmyra palm shell and redgram stalk): characterization of the physicochemical properties and mechanical strength of binderless pellets

To increase the utilization of agro-waste as solid fuel, torrefaction is an important process to improve the fuel properties. In the present investigation, palmyra palm shell (PPS) and redgram stalk (RS) were torrefied in a specially designed stainless-steel tubular reactor with varying temperatures (230 °C, 260 °C, and 300 °C) under a nitrogen atmosphere at two residence times of 30 and 60 min. The influence of torrefaction temperature and residence time on mechanical properties and moisture reabsorption tendency of the binderless pellets were investigated. With increasing the torrefaction temperature up to 300 °C (60-min residence), the mass and energy yield decreased, and the fixed carbon, high heating value, and energy density increased. The fuel ratio (FR) increased from 0.25 or 0.23 to 1.35 and 0.52 for PPS and RS, respectively. The combustibility index increased up to a certain temperature (260 °C); however, at 300 °C, it decreased. Grindability of the torrefied biomass increased; about 99.89% and 95.28% of the smallest particles’ fraction pass through a < 75-µm sieve for PPS and RS, respectively, at 300 °C and 60 min as compared to the raw agro-wastes. The moisture reabsorption tendency of untorrefied and torrefied PPS and RS pellets was measured under the controlled environment of 60% RH at 40 °C. FTIR study supported the hydrophobicity of the torrefied material than the raw biomass. This study demonstrated that the torrefied PPS and RS have fuel properties comparable with India lignite, and this renewable fuel could be sustainably used for power generation and domestic applications.

Effect of the Fuel Equivalence Ratio on the Mechanisms of Thiophene Oxidation in Water Vapor at Increased Density of the Reagents.

The article presents the results of a study of thiophene oxidation in high-density C4H4S/O2 mixtures (ρThi = 0.12 and 0.15 mol/dm3, ρO2 = 0.74–1.26 mol/dm3), diluted with water vapor and argon (dilution level xD = 35–65% mol), at uniform heating (1 K/min) of a stainless-steel tubular reactor up to 823 K. It is established that the temperature of thiophene oxidation onset weakly depends on the nature of the diluent and the oxygen content in the reaction mixture. From the time dependences of the reaction mixtures on temperature and pressure, it follows that the oxidation of thiophene in the water vapor and argon media proceeds according to the mechanisms of homogeneous and heterogeneous reactions. Upon oxidation of thiophene in the stoichiometric mixtures in argon with a small amount of water vapor, as well as in the lean mixtures in water vapor, the contribution of reactions on the surface of the Pt–Rh/Pt thermocouple, inserted into the center of the reaction volume, is increased. Upon oxidation of thiophene in water vapor in the fuel-enriched and stoichiometric mixtures, reactions on the oxidized surface of the reactor wall (primarily iron oxides) prevail. Increasing the density of water vapor both reduces the contribution of heterogeneous reactions on the reactor wall and prevents complete carbon burnout. It is shown that the neutralization of sulfuric acid, resulting from the oxidation of thiophene, with calcium carbonate reduces the corrosion of stainless steel. The X-ray diffraction analysis revealed the presence of ferrochromite, iron and chromium oxides, iron, nickel, and chromium sulfates in the corrosion products.

Colloidal Particles for Pickering Emulsion Stabilization Prepared via Antisolvent Precipitation of Lignin-Rich Cocoa Shell Extract.

This study concerns the preparation and functionality testing of a new class of Pickering particles for food emulsion stabilization: colloidal lignin-rich particles (CLRPs) derived from ethanol-soluble extract of cocoa shell. A further goal was to achieve Pickering functionality without the need to add co-emulsifying surfactants during emulsion processing. Cocoa shell is a co-product of the food manufacturing industry. As such it is anticipated that the particles would be accepted as a natural food ingredient, provided no harmful solvents are used in any step of their processing. The cocoa shell particles were milled, dispersed in water and exposed to 250 °C for 1 h in a stainless-steel tubular reactor followed by ethanol extraction to obtain a lignin-rich extract (46% (w/w) lignin with the remainder predominantly lipids). CLRPs were then fabricated by the precipitation of ethanol-dissolved extract into water (antisolvent). By employing an agitated process and droplet dosing into a non-agitated process, four particle suspensions of a range of submicron diameters were obtained. All particle suspensions contained the same mass fraction of extract and were surface active, with surface tension decreasing with increasing particle size. The smallest particles were obtained when lipids were removed from the extract prior to particle processing. In contrast to the other four particle suspensions, this one failed to stabilize a 10% (w/w) sunflower oil-in-water emulsion. We hypothesize that the phospholipids indigenously present in these CLRP formulations are a critical component for Pickering functionality. It can be concluded that we have successfully introduced a new class of Pickering particles, fabricated from an industry co-product and anticipated to be food grade.

Production of bio-oil and bio-char from pyrolysis of sawdust wood waste (SWW)

AbstractThis study deals with fast pyrolysis of sawdust wood waste (SWW) at the range of temperature 300–700 °C in a stainless steel tubular reactor. The aim was to experimentally investigate how the temperature, the particle size, the nitrogen flow rate (N2) and the heating rate affect bio-oil, bio-char and gaseous products. These parameters were varied in the ranges of 5–20 °C/min, below 0.1–1.5 mm and 20–200 mL min−1, respectively. It was concluded that both the temperature and heating rate have a significant effect on both yield of bio-oil and bio-char resulting from pyrolysis of SWW. The liquid products obtained at various pyrolysis temperatures were subjected into column chromatography after removal of asphaltenes (hexane insoluble). Obtained bio-oils (maltenes or hexane soluble) were classified as aliphatic, aromatic and polar sub-fractions. The maximum of bio-oil yield of 39.5 wt% was obtained at a pyrolysis temperature of 500 °C, particle size between 0.5 and 1 mm, nitrogen flow rate (N2) of 100 mL min−1 and heating rate of 5 °C/min. Liquid product (bio-oil) obtained under the most suitable and optimal condition was characterized by elemental analysis, Nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), Fourier transformed infrared spectroscopy (FT-IR). The analysis of liquid showed that bio-oil from SWW could be a potential source of renewable fuel production and value added chemical. The yield of char generally decreases with increasing the temperature, the char yield passes from 54.61 to 29.47 wt% at the heating rate of 5 °C/min and from 50.01 to 24.5 wt% at the heating rate of 20 °C/min at the same range of temperature (300–700 °C). Solid products (bio-char) obtained in the presence of nitrogen (N2) contain a very important percentage of carbon and high heating values (HHVs).

Pyrolysis of brown algae (Bifurcaria Bifurcata) in a stainless steel tubular reactor: From a review to a case study

This article deals with fast pyrolysis of brown algae, such as Bifurcaria Bifurcata at the range of temperature 300–800 °C in a stainless steel tubular reactor. After a literature review on algae and its importance in renewable sector, a case study was done on pyrolysis of brown algae especially, Bifurcaria Bifurcata. The aim was to experimentally investigate how the temperature, the particle size, the nitrogen flow rate (N2) and the heating rate affect bio-oil, bio-char and gaseous products. These parameters were varied in the ranges of 5–50 °C/min, below 0.2–1 mm and 20–200 mL. min–1, respectively. The maximum bio-oil yield of 41.3wt% was obtained at a pyrolysis temperature of 600 °C, particle size between 0.2–0.5 mm, nitrogen flow rate (N2) of 100 mL. min–1 and heating rate of 5 °C/min. Liquid product obtained under the most suitable and optimal condition was characterized by elemental analysis, 1H-NMR, FT-IR and GC-MS. The analysis of bio-oil showed that bio-oil from Bifurcaria Bifurcata could be a potential source of renewable fuel production and value added chemicals.

Fast Synthesis of SSZ-24: A Pure Silica Zeolite with AFI Framework

Synthesis of SSZ-24, a pure silica zeolite with AFI framework, usually takes a considerably long hydrothermal period by conventional method. Herein, we report a fast synthesis of the SSZ-24 zeolite in 60 min, which was realized by combining the feature of fast heating in a stainless steel tubular reactor with seeding strategy under higher synthesis temperature. In addition, the fast synthesis method showed an advantage, compared with the conventional method, in inhibiting the concurrent crystal growth of impurity phase.

Properties of bio-oil and bio-char produced by sugar cane bagasse pyrolysis in a stainless steel tubular reactor

In this study, compositional analysis of the products obtained by thermal degradation of sugar cane bagasse at various pyrolysis temperatures (300, 350, 400, 450, 500, 550, 600, 650, 700, 750 and 800 °C) and heating rate (5, 10, 20 and 50 °C/min) was studied. Sugar cane bagasse was pyrolyzed in a stainless steel tubular reactor. The aim of this work was to experimentally investigate how the temperature and heating rate affects liquid and char product yields via pyrolysis and to determine optimal condition to have a better yield of these products. Liquid product (bio-oil) obtained under the most suitable conditions were characterized by elemental analysis, FT-IR, C-NMR and HNMR. In addition, column chromatography was employed to determine the aliphatic fraction (Hexane Eluate); gas chromatography and FT-IR were achieved on aliphatic fractions. For char product (bio-char), the elemental chemical composition and yield of the char were determined. The results of our work showed that the amount of liquid product (bio-oil) from pyrolysis of sugar cane bagasse increases with increasing the final temperature and decreases with increasing the heating rate. The highest yield of liquid product is obtained from the samples at 550 °C and at the heating rate of 5°C/min, the maximal average yield achieved almost 32.80 wt%. The yield of char generally decreases with increasing the temperature, the char yield passes from 39.7 wt% to 21 wt% at the heating rate of 5°C/min and from 32 wt% to 17.2 wt% at the heating rate of 50 °C/min at the same range of temperature (300–800 °C). The analysis of bio-oil showed the presence of an aliphatic character and that it is possible to obtain liquid products similar to petroleum from sugar cane bagasse waste. The solid products (bio-char) obtained in the presence of nitrogen (N2) contain a very important percentage of carbon and high higher heating values (HHV).

Investigations on the thermal decomposition of JP-10/iso-octane binary mixtures

To mainly investigate the initiation effect of iso-octane as an activation component on the binary model fuels of JP-10/iso-octane, the thermal decomposition of JP-10, iso-octane and their mixtures has been performed in a stainless-steel tubular reactor at the temperatures from 883K to 963K. The conversions of components, and the yields of gas and liquid products for each sample are determined in detail. The addition of iso-octane can promote the decomposition of JP-10, and the initiation (of JP-10)-inhibition (of iso-octane) effects can be observed during the decomposition processes of JP-10/iso-octane mixtures. One possible mechanism has been proposed to demonstrate the initiation effect of iso-octane on the decomposition of JP-10. For the possible pathways, the rate constants of the H-abstraction reactions between the alkyl radicals obtained from CC bond fission of iso-octane and the H atoms of JP-10 are calculated from the density functional theory (DFT). In combination with the quantum calculations and experimental observations, the formation of some decomposition products in the JP-10/iso-octane mixtures can be reasonably illustrated.

利用微型可视毛细管反应器测定物质在高温高压水中溶解度

Some meaningful achievements have been made on the solubilities of inorganic salts and organic compounds in sub- and supercritical water. But the solubility data remain too scarce to meet the need of modern industry due to the harsh of experimental conditions,equipment requirements and experimental operations,which greatly affects the research and development processes of sub- and supercritical fluid technology in chemical synthesis,extraction and separation,environmental engineering and many other fields. Basic researches still need to be carried out to determine the solubility data and its influence factors of substances in sub- and supercritical water. This paper reviews the research advances of inorganic salts and organic compounds solubility in sub- and supercritical water. The developments of the solubilities of inorganic salts and organic compounds in sub- and supercritical water in fused silica capillary reactor,instead of the traditional stainless steel autoclave or tubular flow reactor,combined with microscopic observation,heating-cooling stage,real-time digital video and in-situ Raman designed by author's group are highlighted in this paper.

Effects of selected amino acids and water-soluble vitamins on acrylamide formation in a ripe olive model system

A ripe olive model system was used to evaluate the potential inhibiting effects on acrylamide formation from a set of amino acids and water-soluble vitamins. The system was based on ripe olive juice heated at 121°C for 30min in a stainless steel tubular reactor. The most potent acrylamide inhibitors were proline and sarcosine, both with inhibition rates of ∼75% at a 100mM level. In addition, glycine, ornithine, taurine, and γ-amino butyric acid were effective (50–65% inhibition) while the rest of the compounds demonstrated weak or non-significant effects. Acrylamide contents in the model system were found to be highly correlated with the corresponding contents in the real product. The kinetic pattern for the formation of acrylamide in the absence and presence of two selected amino acids, added separately or together, was well fitted using a simple logistic function.

Hydroisomerization performance of platinum supported on ZSM-22/ZSM-23 intergrowth zeolite catalyst

Hydroisomerization catalysts Pt/ZSM-22, Pt/ZSM-23, and Pt/ZSM-22/ZSM-23 were prepared by supporting Pt on ZSM-22, ZSM-23, and intergrowth zeolite ZSM-22/ZSM-23, respectively. The typical physicochemical properties of these catalysts were characterized by X-Ray Diffraction (XRD), N2 absorption-desorption, Pyridine-Fourier Transform Infrared (Py-FTIR), Transmission Electron Microscopy (TEM), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM) and NH3-Temperature Programmed Desorption (NH3-TPD), and the performance of these catalysts in n-dodecane hydroisomerization was evaluated in a continuous down-flow fixed bed with a stainless steel tubular reactor. The characterization results indicated that the intergrowth zeolite ZSM-22/ZSM-23 possessed the dual structure of ZSM-22 and ZSM-23, and the catalyst Pt/ZSM-22/ZSM-23 had similar pores and weak acidity to Pt/ZSM-22 and Pt/ZSM-23 catalysts. Moreover, Pt/ZSM-22/ZSM-23 catalyst showed a high selectivity in hydroisomerization of long chain n-alkanes to mono-branched isomers. The evaluation results for n-dodecane hydroisomerization indicated that the activity of Pt/ZSM-22/ZSM-23 was the lowest, while the hydroisomerization selectivity was the highest among the three catalysts. The maximum yield of i-dodecane product was 68.3% over Pt/ZSM-22/ZSM-23 at 320 °c.

Integrated Continuous Processing and Flow Characterization of RAFT Polymerization in Tubular Flow Reactors

AbstractSeveral unit operations are combined in series to form an integrated, continuous polymerization process; namely inline degassing of monomer stock solution prior to reaction, polymerization using the RAFT approach and precipitation after reaction to form a solid polymeric product. The polymerization is conducted at 70–80 °C with reaction times of 30–90 min in a stainless steel tubular flow reactor, yielding poly(acrylamide) at high conversion (typically &gt;90%) and with a low polydispersity of 1.14–1.23. The axial dispersion occurring inside the tubular flow reactor during polymerization is characterized by reaction profiling using a series of NMR samples. The process can be scaled up to a total output of 1.36 kg of polymer per day on this laboratory‐scale reactor. magnified image

Kinetic Analysis for the Degradation of Glycyl-L-leucine andL-Leucyl-glycine in Subcritical Water

Two dipeptides, glycyl-L-leucine (G-L) and L-leucyl-glycine (L-G), the concentrations of which were 10 mmol/L, were degraded in subcritical water in order to understand fully the phenomena occurring during treatment. Treatment was administered in a stainless steel tubular reactor, which was connected to an HPLC pump and immersed in an oil bath at 200-240 °C, with residence times of 10-180 s. When G-L and L-G were treated, L-G and G-L significantly formed, respectively, and then they gradually decreased at every temperature. Irrespective of the kind of substrate, ring formation occurred, and cyclo-(glycyl-L-leucine) was one of the final products. The reaction rate constants related to degradation were estimated under the assumption that all the reactions obeyed first-order kinetics, and the simulated results corresponded well with the experimental ones in every case.

Investigating the influence of extractives on the oil yield and alkane production obtained from three kinds of biomass via deoxy-liquefaction

The aim of this study is to investigate the influence of extractives on the yield and composition of oil obtained from biomass samples (Artemisia ordosica, corn stalk and wheat straw). Direct deoxy-liquefaction experiments of original and extracted biomass were performed at certain temperature in a stainless steel tubular reactor. Benzene–alcohol solvent extraction had significant effect on the product distribution of biomass, especially on the yield and composition of the product oils. The oil yield of original biomass and alkane content in the oil were in the range of 5.44–9.27% and 8.23–23.64%, while decreased to 3.83–4.45% and 1.07–6.03% for the extracted biomass. This study concludes that most of alkanes in the oil mainly derive from the decomposition of triglyceride and hydrocarbon existed in the extractives of biomass. The results might be helpful to study the origin of alkanes and benzene derivatives in the oil obtained from biomass via direct deoxy-liquefaction.