Steel Reactor Research Articles

Effect of the Reactor Material on the Reforming of Primary Syngas.

Syngas, mostly hydrogen and carbon monoxide, has traditionally been produced from coal and natural gas, with biomass gasification later emerging as a renewable process. It is widely used in fuel synthesis through the Fischer-Tropsch (FT) process, where the H2/CO ratio is crucial in determining product efficiency and quality. In this sense, this study aimed to reform an emulated syngas resulting from the supercritical water gasification of biomass, tailoring it to meet the H2/CO ratio required for FT synthesis. Conditions resembling dry reforming were applied, using temperatures from 600 to 950 °C and steel wool as a catalyst. Additionally, the effects of Inconel and stainless steel as reactor materials on syngas reforming were investigated. When Inconel was used, H2/CO ratios ranged between 1.04 and 1.84 with steel wool and 1.28 and 1.67 without. When comparing reactions without steel wool performed either in the Inconel or the stainless steel reactors, those using Inconel consistently outperformed the stainless steel ones, achieving CH4 and CO2 conversions up to 95% and 76%, respectively, versus 0% and 39% with stainless steel. It was concluded that the Inconel reactor exhibited catalytic properties due to its high nickel content and specific oxides.

Measurement of gamma field inside the biological concrete shielding of VVER-1000 Mock-Up at the LR-0 reactor

The long-term operation of existing nuclear power reactors is a crucial concern due to the complexities and expenses associated with replacing key components, such as the reactor pressure vessel and reactor internals. Gamma radiation, a byproduct of nuclear reactions and radioactive decay, significantly influences the lifetime of these components. This radiation is responsible for various degradation pathways leading to void swelling in steel reactor components and cracking or other radiation damage in concrete structures.A study conducted at a full-scale mock-up of the VVER-1000 reactor at the LR-0 zero-power reactor employed HPGe and stilbene measurements to analyze gamma spectra behind the reactor pressure vessel and within concrete biological shielding. While simulations behind the reactor pressure vessel aligned with measurements, notably, amarked overestimation of stilbene spectrum calculations occurred deep in concrete, suggesting potential inaccuracies in radiation predictions for power plant structures.

KINETIC STUDY OF ESTERIFICATION CATALYZED WITH ALUMINUM SULFATE AIMED AT CONVERTING LEVULINIC ACID INTO METHYL LEVULINATE

Recycling lignocellulosic biomass is a sustainable alternative to the petrochemical industry since it allows the production of valuable, sustainable, and environmentally friendly chemical products, such as levulinic acid (LVA) and levulinate esters. Methyl levulinate (MLV), for example, has been assessed as a fuel additive with low toxicity, high lubricity, and flash point stability. In this respect, the present investigation details a kinetic study of methyl esterification catalyzed with aluminum sulfate aimed at converting levulinic acid into methyl levulinate. The reactions were carried out in a Parr Instruments stainless steel reactor to assess the effect of temperature (120, 140 and 160 °C) and reaction time (30, 60, 120 and 180 min) on LVA conversion into MLV, maintaining a constant LVA:methanol ratio of 1:8 and aluminum sulfate catalyst concentration of 0.04 mol.L-1. The maximum LVA-MLV conversion of 93.04 % was obtained at a temperature of 160 °C and reaction time of 60 minutes. The pseudo first-order kinetic model exhibited the best fit to the experimental data, with correlation coefficients (R²) greater than 0.96, and it was used to calculate activation energy, obtaining a value of 10.19 kcal.mol-1.

Radiofrequency Induction Heating for Green Chemicals Manufacture: A Systematic Model of Energy Losses and a Scale-Up Case-Study.

Radiofrequency (RF) induction heating has generated much interest for the abatement of carbon emissions from the chemicals sector as a direct electrification technology. Three challenges have held back its deployment at scale: reactors must be built from nonconductive materials which eliminates steel as a design choice; the viability of scale-up is uncertain; and to date the reported energy efficiency has been too low. This paper presents a model that for the first time makes a comprehensive analysis of energy losses that arise from RF induction heating. The maximum energy efficiency for radio frequency induction heating was previously reported to be 23% with a typical frequency range of 200-400 kHz. The results from the model show that an energy efficiency of 65-82% is achieved at a much lower frequency of 10 kHz and a reactor diameter of 0.2 m. Energy efficiency above 90% with reactor diameters above 1 m in diameter are predicted if higher voltage radio frequency sources can be developed. A new location of the work coil inside of the reactor wall is shown to be highly effective. Losses arising from heating a steel reactor wall in this configuration are shown to be insignificant, even when the wall is immediately adjacent to the work coil. This analysis demonstrates that RF induction heating can be a highly efficient and effective industrial technology for coupling high energy demand chemicals manufacture electricity from zero carbon renewables.

Comparison of the corrosion behaviour of 10Cr and 17Cr Al added ODS steel in simulated reprocessing nitric acid medium

It is imperative to comprehend the corrosion behavior of different Cr containing Al-added ODS steel reactor clad materials in nuclear reprocessing simulating conditions, as high dissolution of clad material is not desirable. In this present work, the effect of varying HNO3 concentrations (3, 6, 11.5 M HNO3) and with oxidizing (Cr6+, Ce3+) and non-oxidizing (Fe3+) ions in 6 M HNO3 on 10Cr (10Cr-5Al-0.5Ti-0.5Y2O3-Fe) and 17Cr (16.78Cr-4.46Al-0.5Ti-0.45Y2O3-Fe) Al-ODS steels are investigated. The potentiodynamic anodic polarization studies revealed an ennoblement of corrosion potential by elevated cathodic current resulting from increased oxidizing conditions in HNO3 by concentration and oxidizing ions. Through various electrochemical techniques like open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), the 17Cr Al-ODS steel exhibited improved corrosion resistance with lower Ecorr, increased passivation range (Epass range), lower corrosion current density (icorr) and increased charge transfer resistance (Rct). The SEM studies revealed variation in corrosion morphology as shallow corrosion cavities and deeper corrosion pits in 17Cr Al-ODS and 10Cr Al-ODS steel, respectively, at high oxidizing environment. The enhanced corrosion resistance of 17Cr Al-ODS is associated to the improved passivation with the high Cr level in the steel compared to 10Cr-ODS steel, which is corroborated by XPS analysis. New knowledge on nitric acid corrosion mechanism on the Cr in Al-ODS steels and the influences of oxidizing ions in reprocessing environments are described.

Uptake and coordination behaviour of uranyl on functionalised silica

The safe decommissioning of nuclear reactors is a complex process, requiring a range of technological options for it to be done effectively. It has become more important in recent years, with the substantial number of reactors entering the decommissioning phase. This paper details the use of functionalised silica for the recovery of uranium from aqueous hydrochloric acid solutions, a potential agent for the treatment of steel reactor components during nuclear reactor decommissioning. Silica functionalised with either phosphonic acid, bistriazine, or bistriazinylbipyridine ligands was shown to extract uranium, with the commercially available phosphonic acid functionality being the most effective. Extractions of 100 % were observed at [H+] ≤ 0.24 M, further the phosphonic acid functionality also had the highest loading capacity. Increasing [H+] has a suppressive effect on uranyl recovery, which was more pronounced for the in-house synthesized silica, and was attributed to protonation of the extracting moiety. Extended x-ray absorption fine structure spectroscopy was also used to determine the uranium coordination environments on the functionalised silica, and gain insights into the extraction mechanism. The uranyl cation was bound by two phosphonic acid groups, two bis-triazine groups, and one bistriazinylbipyridine group, respectively on each respective extractant. Uranyl was found to be penta-coordinate in the equatorial plane for all systems, with oxygen and/or chloride always present in the first coordination sphere. Evaluation of the mechanism indicated that uranyl must be loading onto the phosphonic acid functionality via multiple mechanisms, to both the phosphonic acid and silica related surface groups, although preferential binding of uranyl to the phosphonic acid groups was observed.

Onboard Miniature Jet Fuel Desulfurizer for Mobile Fuel Cell Power Systems

Owing to its high energy density and wide availability, jet fuel is a promising fuel for solid oxide fuel cell (SOFC) power systems. However, fuel‐reforming catalysts and SOFC anodes are easily poisoned by sulfur compounds present in the jet fuel. Therefore, effective removal of sulfur from the jet fuel is essential before its feeding to the SOFC system. Herein, a novel adsorptive desulfurization reactor for onboard desulfurization of jet fuel in mobile SOFC systems is developed. A laser‐based 3D printing method is used to fabricate the one‐piece stainless steel reactor that significantly simplifies the assembly and reduces the overall weight. The desulfurization performance of the reactor is evaluated using a regenerable nickel‐based sorbent under varying operating conditions. A strong influence of temperature and fuel flow rate on the desulfurization performance is observed. The results confirm that the developed desulfurization system is capable of reducing the sulfur content in jet fuel to a few ppm to sub‐ppm level. The proposed desulfurization system offers unique advantages in terms of geometric design flexibility, space optimization, scalability, and modularity for any onboard and/or on‐demand deep desulfurization needs in addition to fuel cell power systems for transport and portable applications.

Sustainable utilization of value-added products from the catalytic and non-catalytic pyrolysis of motor car scrap tire: Suitability of produced char for energy generation and sugar mill wastewater treatment

Clean fuel and sustainable energy utilization are essential requirements to address the impacts of global warming and climate change. In this study, the pyrolysis of motor car scrap tire was investigated in a fabricated cylindrical stainless steel reactor, operated at 450, 500, and 550 °C for 50 min with or without the addition of a catalyst. The catalytic condition yielded maximum char of 59% w/w obtained at 450 °C. The addition of the catalyst also enhanced oil yield up to 33% w/w at 500 °C while the maximum gas fraction of 44% w/w was obtained under the non-catalytic condition, at 550 °C. The TGA/DSC analysis showed that the pyrolysis char had a specific heat capacity (Cp) of 35 J/g.K, relating to its high thermal stability for applications in furnaces, reactors, and heat construction materials. The char, after chemical activation, with the XRD analysis, showed that the produced activated carbon (AC) has a good crystalline structure (with high interplanar distances). The BET analysis revealed that the AC has a high surface area of 1065 m2/g (average pore diameter of 3.36 nm) which enhanced the adsorption capacity of the AC to about 90 % efficiency for the removal of the heavy metal, cadmium, from sugar mill wastewater.

Steam cracking of sulfur containing compounds: A fundamental modelling study

Sulfur-containing additives are commonly used in industrial steam cracking to mitigate carbon monoxide (CO) formation. Their impact on solid coke deposition in reactors is well-studied but not fully understood. This study investigates the decomposition of five common sulfur compounds (DMDS, DMS, DMSO, CS2, COS) in both inert and hydrocarbon environments within the steam cracking industry. To achieve this, an in-house automated network generation tool called Genesys and a validated ab initio methodology at the CBS-QB3 level are used. This combination generates a comprehensive kinetic model with precise thermodynamic and kinetic parameters. The kinetic model is rigorously validated against experimental data from prior studies under various conditions, including inert nitrogen atmospheres and hydrocarbon matrices (using ethane and heptane). Experimental setups involve bench-scale annular quartz reactors and pilot-scale stainless steel reactors. Remarkably, the kinetic model accurately predicts primary products and captures secondary product trends across diverse conditions without parameter adjustments. Rate of production analyses reveal critical decomposition pathways during sulfur-containing additive pyrolysis and the influence of hydrocarbon matrices. Notably, these additives primarily yield H2S upon decomposition, with CS2, SO2 and thiophene as minor products. In conclusion, the developed fundamental kinetic model accurately predicts product formation during the pyrolysis of DMS, DMDS, DMSO, CS2 and COS, whether in nitrogen or a hydrocarbon matrix, without altering core thermodynamic and kinetic parameters.

Pyrolysis and catalytic steam gasification of olive oil waste in two stages

A study of the pyrolysis and catalytic gasification of a waste from the extraction of olive oil has been carried out. The work objective was to characterize the solid and gaseous phases generated in the process for their possible utilization in energy generation. The experimental system consists of two cylindrical stainless steel reactors connected in series. A conventional pyrolysis is produced in the first reactor. In the second reactor, the gases and liquids generated in the first one pass through a dolomite catalytic bed where the cracking of the heavier components is produced. Also, in this second reactor, a steam stream is continuously introduced. The influence of temperature (500-700 ºC), quantity of catalyst (25-100 g) and steam flow rate (0-1.40 mL/min) has been determined. Also, the dolomite effectiveness as catalyst was evaluated For this motive, experiments, without reactivating dolomite, were carried out (0-6 runs), and the yields of solids, liquids and gases were determined. An increase in reaction temperature leads to a decrease in solid and liquid yield and to an increase in the gas phase yield. The presence of catalyst and the quantity of the same, originate an important decrease in the liquid phase yield and a high increase in the gas phase yield, especially important in the case of hydrogen. On the other hand, the catalyst is very stable and does not lose activity during at least six cycles of reaction. The presence of steam, increase the yield of hydrogen, but the increase of the steam flow rate, do not generate significant changes in the products distribution.

Numerical simulation of inductively coupled Ar/O<sub>2</sub> plasma

In the inductively coupled plasma (ICP) discharge, surface processes, such as reflection, de-excitation, and recombination, can occur when active species arrive at material surfaces, which accordingly influences the plasma properties. In this work, a fluid model is used to study the Ar/O<sub>2</sub> plasma generated by ICP reactors made of different materials. In simulation, sticking coefficient is employed to estimate the surface reactions on different materials. As the reactor material changes from stainless steel to anodized aluminum to Cu, the sticking coefficient of surface reaction O→1/2O<sub>2</sub> decreases accordingly. It is found that the reactor material has a great effect on species density. In the stainless steel reactor, the density of O atoms at grounded state and excited state are much lower because more O<sub>2</sub> molecules are generated from the surface reaction, yielding a much higher density of <inline-formula><tex-math id="M5">\begin{document}$ {\text{O}}_2^ + $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M5.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M5.png"/></alternatives></inline-formula> molecular ions which are mainly created from the ionization process of O<sub>2</sub> molecules. Similarly, the high density of O<sub>2</sub> molecules also enhances the production of <inline-formula><tex-math id="M6">\begin{document}${{{\mathrm{O}}} _2}\left( {{{\mathrm{a}}^1}{\Delta _{\mathrm{g}}}} \right)$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M6.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M6.png"/></alternatives></inline-formula> molecules through the excitation process and O<sup>–</sup> ions through the dissociation attachment reaction. On the contrary, more electrons are consumed via the collisions between electrons and O<sub>2</sub> molecules or <inline-formula><tex-math id="M7">\begin{document}$ {\text{O}}_2^ + $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M7.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M7.png"/></alternatives></inline-formula> molecular ions. Therefore, the electron density obtained in the Cu reactor is highest. The density of Ar<sup>+</sup> ions and Ar<sub>m</sub> atoms also increase with sticking coefficient decreasing. The density of O<sup>+</sup> ions and <inline-formula><tex-math id="M8">\begin{document}$ {\text{O}}_2^ + $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M8.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M8.png"/></alternatives></inline-formula> molecular ions peak below the coil in the stainless steel reactor, whereas the radial uniformities are improved in the Cu reactor. In the three reactors, the electrons distribute evenly at the reactor center region. The O density and <inline-formula><tex-math id="M9">\begin{document}${{{\mathrm{O}}} _2}\left( {{{\mathrm{a}}^1}{\Delta _{\mathrm{g}}}} \right)$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M9.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="13-20240436_M9.png"/></alternatives></inline-formula> density significantly peak at the reactor center, while the maximum value of Ar<sup>+</sup> density and Ar<sub>m</sub> density are below the coil. As for O(<sup>1</sup>D), the maximum density below the coil region moves toward the reactor center as the reactor material changes from stainless steel to Cu. Finally, the effect of sticking coefficient of O→1/2O<sub>2</sub> is studied. The results show that the O atom density decreases with the sticking coefficient increasing, but the opposite trend is observed in O<sub>2</sub> molecular density. It is noticed that the sticking coefficient has little effect on species density when it is higher than 0.5.

COMBINED SLAB-PILE FOUNDATION

Solid reinforced concrete slab foundations are commonly employed in the construction of multi-story frame and panel buildings on natural grounds, as well as in industrial structures such assilos, elevators, chimneys, steel reactors, and more.One significant advantage of monolithic foundations is their ability to be used on weak and uneven ground bases. These foundations can distribute uneven loads over a considerable area, redistributingthem to equalize the inevitable differential settlements of individual foundations. On soft and uneven soils, slab foundations are not only used to mitigate deformations but also to protect against highgroundwater, creating what is known as a "floating" foundation.It has been demonstrated that the combined slab pile foundation (CSPF) is an effective development in the field of foundation construction. CSPF constitutes a foundation system comprising a "pile field – slab grillage – soil base," where piles bear a portion of the building load, and the slab grillage functions as a foundation slab. CSPF can be interpreted as a monolithic slab supported by piles of various types arranged in the form of a pile field, strips,clusters, or individual piles. Various types of piles, including "barrette" piles, can be used for CSPF foundations.Considering the soil resistance beneath the slab grillage in the deformation calculations and loadbearing capacity of combined slab-pile foundations provides a reserve for enhancing their economic efficiency. This includes reducing the number ofpiles, lowering the consumption of steel reinforcement, and decreasing the thickness of the grillage.However, the implementation of CSPF in construction is hindered by the limited theoretical research, necessary regulatory framework, and design experience for such structures.The determination of design parameters for CSPF is carried out using the method of successive approximations. By specifying the area of the slab grillage and defining the pile length and spacing, the number of piles in the foundation, the settlement ofan individual pile, and the design load on the pile are calculated (initially assuming that all piles bear 70-80% of the total load).

Hydrotreatment of Eucalyptus sawdust: The influence of process temperature and H2SO4 catalyst on hydrochar quality, combustion behavior and related emissions

Hydrothermal carbonization (HTC) presents a promising avenue for waste-to-energy conversion, owing to its cost-effectiveness, low emissions, and adaptability. This study employed HTC to convert Eucalyptus grandis sawdust residues into hydrochars (HC). HTC was conducted for 60 min in a high-pressure steel reactor within glycerin thermal bath equipment under different temperatures (150, 170, 190, and 220 °C) and reaction mediums (water and H2SO4 concentrations of 0.1 and 0.2 mol L–1). The resulting HC underwent thorough analysis, encompassing proximate, ultimate, and morphological assessments and investigations into combustion behavior and potential emissions. Moreover, a new indicator, the hydrotreatment severity index (HSI), is proposed to provide a standardized measure of hydrotreatment severity and property predictions. Higher temperatures and increased H2SO4 concentrations were found to reduce solid yield (ranging from 43.21 % to 90.72 %) and induce morphological changes, including an abundance of carbon microspheres, particularly at higher acid concentrations. These modifications substantially improved higher heating values (HHV), up to 34 % (HHV of 25.72 MJ kg−1 achieved at 220 °C with 0.2 mol L–1 H2SO4) compared to raw feedstock. Interestingly, the intermediate temperature of 190 °C contributed significantly, enhancing HHV by 33 %. All HTC processes greatly enhanced the combustion performance and ignitability of hydrochars. The most favorable reactivity (S = 7.61E7 %2 min−2 °C−3) was observed at 220 °C with 0.2 mol L–1 H2SO4, along with an estimated CO2 emissions of 2,058.46 kg per ton of hydrochar. These results underscore the efficacy of the simplified methodology and reactor system, emphasizing the critical roles of H2SO4 as catalyst and temperature in shaping the characteristics and performance of hydrochars from a representative Brazilian residue, Eucalyptus grandis.

Simultaneous Delignification and Furfural Production of Palm Oil Empty Fruit Bunch by Novel Ternary Deep Eutectic Solvent

The most considerable solid waste from crude palm oil plants is oil palm empty fruit bunch (OPEFB) which contains cellulose, lignin, and hemicellulose. Hemicellulose can be hydrolyzed to xylose and then converted to furfural via dehydration. Pretreatment is one of the steps in the bioconversion of lignocellulose material to reduce lignin. This study developed a one-pot process to conduct pretreatment and furfural production simultaneously. This process uses a green solvent called ternary deep eutectic solvent (DES). DES was synthesized by mixing choline chloride, oxalic acid, and ethylene glycol with a molar ratio of 1:1:2 (CHOAEG). Simultaneous delignification and furfural production were carried out in a stainless steel reactor. The temperature was varied at 100, 120, and 150 °C, with the various processing time at 30, 60, and 90 min, respectively. The highest furfural concentration reached 9.68 g/L, and the delignification was achieved up to 55.81% at 150 °C for 90 min. The OPEFB pretreated was hydrolyzed by cellulase and achieved 90.79% glucose yield. Overall, the simultaneous delignification and furfural production process by ternary DES CHOAEG demonstrated a novel and efficient process by reducing the number of complex processes stages of biorefinery lignocellulose.

SYNTHESIS AND STUDY OF THE PROPERTIES OF EPOXYCYCLOCARBONATES BASED ON ACRYLATE-VINYL COPOLYMERS

A method of synthesis of acrylate-vinyl copolymers based on glycidyl methacrylate and styrene at different molar ratios and epoxy cyclocarbonates based on them was developed. Synthesis of styrene-glycidyl methacrylate (СP GMA/St) copolymers was carried out by the method of thermally initiated radical polymerization in steel reactors in the presence of 1% azo-bis-isobutyronitrile initiator at a temperature of 65 °C for 10 hours. The number of epoxy groups in the synthesized СP GMA/St, determined by the potentiometric titration method, naturally decreases with a decrease in the molar ratio of GMA/styrene. The synthesis of СP GMA/St epoxycyclocarbonates was carried out in a high-pressure autoclave by passing CO2 through the reaction mixture of a solution of KP in toluene with a catalyst (tetrabutylammonium bromide 5%) with stirring at a temperature of 110–120 °C, a pressure of (4-5) atm. The structure of СP and ECC was confirmed by IR spectroscopy. No bands of double bonds are observed in the IR spectra of СP GMA/St, there are vibration bands characteristic of oligostyrene and vibration bands of C=O, C–O–C and epoxy groups. During the formation of ECC, new vibration bands of cyclocarbonate groups with a maximum of 1802 cm-1 appear, changes are observed in the absorption region of C–O–C groups (1100–1300) cm-1, and the vibration bands of epoxy groups with a maximum of 843 cm-1 decrease. The study of relaxation transitions in acrylate-vinyl copolymers GMA/St and epoxy cyclocarbonates based on them using the DSC method showed that all samples are amorphous single-phase polymers. After changing the background, the excessive enthalpy observed during the first heating disappears, and the glass transition temperature shifts towards higher temperatures, which indicates the formation of a denser and thermodynamically balanced structure. The thermostability of the synthesized GMA/St copolymers and epoxy cyclocarbons was investigated by the method of thermogravimetry. It was established that all the obtained substances have one stage of weight loss and are heat resistant, since weight loss begins at a temperature above 240 °C. In the future, the obtained epoxycyclocarbonates will be used for the synthesis of polyurethanes by the non-isocyanate method.

Effect of iron-nickel cations on urea-assisted hydrothermal dechlorination of polyvinyl chloride: Appropriateness of using steel reactors for determining intrinsic degradation chemistry

Hydrothermal dechlorination of polyvinyl chloride (PVC) is primarily performed in stainless-steel reactors prone to chlorine-induced pitting corrosion, contaminating the reaction media with Fe2+, Ni2+, and Cr2+ possibly triggering shifts in the degradation chemistry. This study investigated the single and synergistic effects of Fe2+ and Ni2+ on urea-assisted hydrothermal dechlorination of PVC under mild conditions. Significant improvement in dechlorination degree was observed at 210 °C when 5 mmol/L Fe2+ or 10 mmol/L Ni2+ was added. Furthermore, positive interaction between the cations was confirmed when the simultaneous use of 1 mmol/L Fe2+ and 0.25 mmol/L Ni2+ achieved the same catalytic performance. The presence of these ions prevented adhesive contact of PVC particles, thus limiting the mass-transfer resistance and autocatalytic effect. The experimental design revealed that dechlorination and its improvement were temperature-dependent (p < 0.0001). Ni2+ and Fe2+ exerted quadratic and linear effects, respectively, on dechlorination. The highest catalytic activity occurred in the temperature range of 217.5–222.5 °C. The results show that total concentrations of as low as 1.08 mmol/L accelerated dechlorination, indicating the inappropriateness of using steel reactors for determining intrinsic PVC degradation chemistry. However, Fe–Ni composites have the potential to be used as catalysts.

TARGET – Development of Submersible ROV System for BMN Inspection

Most PWRs have penetrations in the RPV lower heads for in-core nuclear instrumentation. These penetrations generally are made of nickel-based Inconel Alloy 600. Weld materials are typically Alloy 82/182. Operating conditions of PWR plants are causing nickel-based alloys cracking through a process called primary water stress corrosion cracking (PWSCC). In 2003, the licensee for the South Texas Project Unit 1 (STP-1) identified apparent boron deposits on the lower RPV head near two bottom mounted nozzles (BMNs). The NRC issued Bulletin 2003-02 to obtain information on licensee inspection activities and inspection plans for the RPV lower head. EPRI issued MRP-206 report that provides inspection and evaluation guidelines for BMNs for PWR plants, including guidelines for periodic bare metal visual examination for evidence of primary coolant leakage, or periodic non-visual nondestructive examinations for indications of service-induced cracking. The non-visual inspections (ultrasonic testing examination) may detect service-induced degradation before through-wall cracking, leakage, circumferential cracking below the bottom of the J-groove weld, release of loose parts, or incipient boric acid wastage of the low-alloy steel reactor vessel lower head material occurs. Therefore, periodic examinations will adequately manage potential for cracking by PWSCC and preserve structural integrity. INETEC developed TARGET system for BMNs inspection, consisted of submersible ROV and specially designed probe, composed of several UT probes. UT system and technique to detect, length and depth size the service-induced degradation in the BMN volume material is developed. The EPRI NDE Center performed a technical review and validated INETEC’s ultrasonic examination technique for BMNs. Aforementioned validation was done according to requirements defined by: 1) MRP-206, 2) MRP-411.

The utilization of rice straw (Oryza Sativa L.) as a green catalyst in the enhanced production of hydrogen via the thermochemical conversion process of shrimp farm sludge

The catalytic mechanism of rice straw, Oryza Sativa L., on the carbonation of shrimp farm sludges via the gasification process was investigated in this work. Rice straw possessed 75% of its weight is silicon dioxide (SiO2) which can be utilized as an effective catalyst whereas the tar decomposition and gas production during the thermochemical process can be enhanced. In that manner, the influence of working temperature (oC), the ratio (%wt) on the amount of rice straw used in the shrimp farm sludges, and the moisture content (%) in the prepared samples are taken into account to determine the role of rice straw catalytic. Gasification processes were carried out in 60 min in a stainless steel reactor, with a feeding rate of 0.5 kg/h and an air-pumped flow rate of 2 L/min. All experiments were performed under different conditions of working temperatures (600, 700, 800, and 900 °C), sample composition (0, 20, 40, and 60 %wt of rice straw added), and moisture content of the feedstock (20, 40, 60, 80, and 90%). It is essential to confirm that the change in sample moisture content and the working temperature are also significant to the production of hydrogen throughout the process. As the moisture content increase from 20 to 40%, the hydrogen yield is proportionally increased by 5–10%. On the aspect of working temperature influence, the hydrogen composition increased from 11% at 600 °C to 27% at 900 °C for the RS sample, from 13% at 600 °C to 29% at 900 °C for the RS20, from 17% at 600 °C to 35% at 900 °C for the RS40 sample, and from 19% at 600 °C to 43% at 900 °C for the RS60 sample. The findings in this work confirm the rice straw catalyst's role in enhancing hydrogen production via the gasification process. Furthermore, this work provides guidance information for simple but effective processes that can not only deal with the sludge waste management issue but also create a waste-to-energy route suitable for medium and small-scale aquaculture businesses.

Combined process of cyclohexyl cyclohexanecarboxylate synthesis from cyclohexanol and CO catalyzed by the Pd(OAc)2–PPh3–p-toluenesulfonic acid system

Objectives. To study the possibility of combining acid-catalytic cyclohexanol dehydration and alkoxycarbonylation of the formed cyclohexene with cyclohexanol and carbon(II) oxide in a single reactor in order to achieve high yields of the target cyclohexyl cyclohexanecarboxylate product under mild conditions using the Pd(OAc)2–PPh3–p-toluenesulfonic acid catalytic system.Methods. The combined process took place in a toluene medium in a periodic steel reactor designed to operate at elevated pressure, equipped with a glass insert, a magnetic stirrer, and a sampler, as well as gas input and discharge devices. The reaction mass with the components of the catalytic system was placed in a glass reactor inside a steel autoclave. The reaction mass samples obtained during the combined process were analyzed by gas–liquid chromatography with a flame ionization detector.Results. The possibility of combining cyclohexanol dehydration catalyzed by p-toluenesulfonic acid monohydrate and formed cyclohexene alkoxycarbonylation with cyclohexanol and CO during catalysis by the Pd(OAc)2–PPh3–p-toluenesulfonic acid system in a single reactor was demonstrated. Under mild conditions (temperature 110°C; CO pressure 2.1 MPa), the target product yield reached 64.8% in 5 h. However, the combined process is complicated by the formation of a cyclohexanecarboxylic acid by-product formed as a result of the cyclohexyl cyclohexanecarboxylate hydrolysis and the cyclohexene hydroxycarbonylation.Conclusions. The reactions of intramolecular acid-catalytic cyclohexanol dehydration and formed cyclohexene alkoxycarbonylation catalyzed by the Pd(OAc)2–PPh3–p-toluenesulfonic acid system can be combined in a single reactor. p-Toluenesulfonic acid can simultaneously act as a catalyst for the cyclohexanol dehydration and a co-catalyst of the palladium–phosphine system of cyclohexene alkoxycarbonylation. The involvement of cyclohexene, representing a product of reversible cyclohexanol dehydration, in the alkoxycarbonylation reaction is a factor in shifting the dehydration reaction equilibrium towards the formation of cyclohexene. Cyclohexanecarboxylic acid is a by-product of the proposed combined process. A factor in the reduction of target product yield is water formed as a result of cyclohexanol dehydration due to the involvement of the latter in the hydrolysis reaction and the course of the cyclohexene hydroxycarbonylation.

4D printing of polyamide 1212 based shape memory thermoplastic polyamide elastomers by selective laser sintering

4D printing technology, also known as additive manufacturing technology for smart devices, offers a wide range of promising applications in aerospace, automobile, biomedical and soft robotics. However, there are only a limited number of commercialized elastomer materials for 3D printing which needs further development, especially smart elastomers. In this work, polyamide 1212 (PA1212) based thermoplastic polyamide elastomer (TPAE) was synthesized by one-pot melt polycondensation of 1,12-dodecanedioic acid (DA), 1,12-dodecanedioic amine (DN) and polyetheramine in a stainless steel reactor and then the TPAE powder for selective laser sintering (SLS) was obtained after freeze-crushing and sieving. Subsequently, the effects of sintering temperature, laser power, layer thickness, and scan spacing during SLS processing on the properties of the sintered parts were fully investigated. The tensile strength, elastic modulus and elongation at break of the sintered parts could reach 13.7 MPa, 124 MPa and 200 %, respectively, when the sintering temperature, laser power, layer thickness and scan spacing were set as 156 °C, 21 W, 0.10 mm and 0.10 mm, respectively. Moreover, PA1212-based TPAEs fabricated by SLS showed excellent and stable shape memory behavior. This work not only provides a designing strategy of 4D printable materials and referential SLS-processing parameters, but also broadens the application of polyamide-based elastomer materials into 4D printing fields.