High-temperature Sulfurization Research Articles

Research and application of surface spray anti-corrosion technology for coiled tubing in pressurized environment

In this study, the corrosion risk of coiled tubing under high pressure, high temperature and high sulfur conditions was investigated, and the protection solution was put forward. In this paper, spray paint is used to prevent corrosion of tubing, and the effects of high temperature desulfurization and nano super absorbent spraying agent are compared. The pressure jet spraying device is designed for uniform spraying during operation to improve corrosion resistance. Determine the best spraying position and monitoring point. The results show that nano-coating agent can prevent cracking and serious corrosion, and its application effect in oil wells meets the requirements. These findings support that anti-corrosion spraying technology on coiled tubing surface can effectively prevent tubing corrosion in high temperature, high pressure and corrosive environment.

CoS2 nanoparticles embedded in N-doped hollow carbon nanotubes as anode materials for high performance lithium-ion battery

CoS2 nanoparticles are effectively incorporated into N-doped hollow carbon nanotubes (CoS2@HC) through a combination of a straightforward oil bath method and a high-temperature sulfurization process. The CoS2@HC composite demonstrates exceptional electrochemical performance as an anode material in Li-ion batteries. The outstanding performance of this system can be attributed to the ingeniously designed hollow carbon nanotubes. These nanotubes not only possess high electrical conductivity, thus facilitating efficient electron transfer, but also provide ample space to accommodate volume changes. Furthermore, the ultrafine CoS2 nanoparticles embedded within the hollow carbon nanotubes offer a large surface area for effective electrolyte wetting and rapid ion diffusion during the cycling process. As a result, the CoS2@HC composite delivers a high capacity of 356.2 mAh·g−1 at 2000 mA·g−1 even after 1500 cycles, demonstrating remarkable cyclic stability.

Binary Atomic Sites Enable a Confined Bidirectional Tandem Electrocatalytic Sulfur Conversion for Low-Temperature All-Solid-State Na-S Batteries.

The broader implementation of current all-solid-state Na-S batteries is still plagued by high operation temperature and inefficient sulfur utilization. And the uncontrollable sulfur speciation pathway along with the sluggish polysulfide redox kinetics further compromise the theoretical potentials of Na-S chemistry. Herein, we report a confined bidirectional tandem electrocatalysis effect to tune polysulfide electrochemistry in a novel low-temperature (80 °C) all-solid-state Na-S battery that utilizes Na3 Zr2 Si2 PO12 ceramic membrane as a platform. The bifunctional hollow sulfur matrix consisting binary atomically dispersed MnN4 and CoN4 hotspots was fabricated using a sacrificial template process. Upon discharge, CoN4 sites activate sulfur species and catalyze long-chain to short-chain polysulfides reduction, while MnN4 centers substantially accelerate the low-kinetic Na2 S4 to Na2 S directly conversion, manipulating the uniform deposition of electroactive Na2 S and avoiding the formation of irreversible products (e.g., Na2 S2 ). The intrinsic synergy of two catalytic centers benefits the Na2 S decomposition and minimizes its activation barrier during battery recharging and then efficiently mitigate the cathodic passivation. As a result, the stable cycling of all-solid-state Na-S cell delivers an attractive reversible capacity of 1060 mAh g-1 with a high CE of 98.5 % and a high energy of 1008 Wh kgcathode -1 , comparable to the liquid electrolyte cells.

Binary Atomic Sites Enable a Confined Bidirectional Tandem Electrocatalytic Sulfur Conversion for Low‐Temperature All‐Solid‐State Na−S Batteries

AbstractThe broader implementation of current all‐solid‐state Na−S batteries is still plagued by high operation temperature and inefficient sulfur utilization. And the uncontrollable sulfur speciation pathway along with the sluggish polysulfide redox kinetics further compromise the theoretical potentials of Na−S chemistry. Herein, we report a confined bidirectional tandem electrocatalysis effect to tune polysulfide electrochemistry in a novel low‐temperature (80 °C) all‐solid‐state Na−S battery that utilizes Na3Zr2Si2PO12 ceramic membrane as a platform. The bifunctional hollow sulfur matrix consisting binary atomically dispersed MnN4 and CoN4 hotspots was fabricated using a sacrificial template process. Upon discharge, CoN4 sites activate sulfur species and catalyze long‐chain to short‐chain polysulfides reduction, while MnN4 centers substantially accelerate the low‐kinetic Na2S4 to Na2S directly conversion, manipulating the uniform deposition of electroactive Na2S and avoiding the formation of irreversible products (e.g., Na2S2). The intrinsic synergy of two catalytic centers benefits the Na2S decomposition and minimizes its activation barrier during battery recharging and then efficiently mitigate the cathodic passivation. As a result, the stable cycling of all‐solid‐state Na−S cell delivers an attractive reversible capacity of 1060 mAh g−1 with a high CE of 98.5 % and a high energy of 1008 Wh kgcathode−1, comparable to the liquid electrolyte cells.

Sulfur-graded kesterite structured film drives improvement of VOC.

Realizing the graded bandgap in absorber layer is very essential for high efficient thin film solar cells. However, such bandgap modification in kesterite-structured Cu2ZnSnSe4 is normally realized via high temperature sulfurization process (above 500°C), which is not only difficult to control the sulfurization depth, but also introduces additional deep defects because of the decomposition of absorber layer at such high temperature. In this study, a low-temperature sulfurization process (150°C) is developed. Such process not only inhibits the decomposition of Cu2ZnSnSe4 films and controls the elemental distribution very well, but also increase the surface bandgap of the absorber layer and form a gradient energy bandgap. Also, the density of deep-level defects in the Cu2ZnSnSe4 layer is reduced. As a consequence, the open circuit voltage of the solar cell is improved by 60 mV. This study paves the way towards the high efficient kesterite solar cell and other solar cells.

Universal pathway towards metal sulfides decorated 3D porous Ti3C2Tx MXene aerogel for vapor-phase mercury removal

Utilization of monolithic mineral sulfide-based sorbent for the fix-bed elemental mercury (Hg0) removal is regarded as a predominant predicament in the field of Hg0 abatement. In this work, a general and facile route was exploited to establish CuS particles decorated 3D porous Ti3C2Tx MXene aerogel via divalent Cu2+ cations induced assembly combined with subsequent high-temperature sulfurization treatment, during which, uniform CuS particles were homogeneously anchored throughout the Ti3C2Tx substrate. The obtained 3D CuS/Ti3C2Tx MXene aerogel exhibited satisfactory textural property, hierarchical pore structure and strong interaction between Ti3C2Tx MXene and CuS. Meanwhile, the inherent restacking of Ti3C2Tx MXene nanosheet and serious agglomeration of CuS can also be effectively avoided in the formation of aerogel. Those structural advantages originating from this novel gelation process favorably contributes to satisfactory Hg0 mass transfer and sufficient utilization of CuS active ligands, which largely strengthens Hg0 removal performance and broadens the fix-bed application of mineral sulfides. Consequently, the Hg0 capture capacity and adsorption rate of CuS/Ti3C2Tx MXene aerogel reached 90596.4 g m−3 and 120.64 g m−3 min−1, respectively, far outbalancing those of the reported in-situ selenized copper foam with excellent Hg0 removal activity. The impressive Hg0 sequestration performance is attributed to its relatively large specific surface area, layered pore channel, and highly dispersed CuS particles, largely boosting Hg0 mass transfer and following sequestration. Moreover, other mineral sulfides/Ti3C2Tx MXene aerogels can also be constructed by just replacing divalent metal cations, which makes the initial effort towards the fix-bed utilization of mineral sulfides-based aerogel for vapor-phase Hg0 immobilization.

Mo–Ni, Mo–Fe and Mo–Ni–W nanoparticles for down-hole upgrading

Patented in situ (in reservoir) upgrading technology (ISUT) converts a portion of the reservoir into a “catalytic reactor” by irreversibly attaching a low percentage of nanoparticles to the reservoir's sand/rock. The nanoparticles are prepared as a dispersion in hot vacuum residue and the hot dispersion is injected into the reservoir with low quantities of hydrogen.MoNi, MoFe and MoNiW nanoparticles suspended in bitumen were prepared, in similar way as in ISUT, and the suspensions treated in a batch reactor. Two different sulfiding agents (ammonium sulfide and thiocarbamide) were added during the preparation of the nanoparticles-bitumen suspension. Particle diameters obtained for the suspensions were determined by NTA. The particles were recovered after reaction and its surface composition determined by XPS. Reaction products were analyzed by high temperature simulated distillation, density, viscosity, sulfur and nitrogen content and stability (P-value). MoNi, MoFe and MoNiW with average sizes of 84, 101 and 93 nm, respectively, were produced. XPS characterization of the Mo–Ni–W particles before reaction showed that Mo and Ni are only partly sulfided, while W was present as WO3. The proportion of the metals in the sulfided state increases after reaction from 39 to 94, 35 to 77 and a 0 to 50 (atomic %) for Mo, Ni and W, respectively. In addition, VR conversions were similar by comparing the thermal and catalytic tests, indicating that VR cracking is mainly thermal. However, viscosity, MCR and S contents were lower, and API gravity was higher when a catalyst was used. Also, catalytic products proved more stable than products obtained from thermal reaction. The reaction carried out using dispersions where thiocarbamide was the sulfiding agent provided products with slightly betterer properties in spite of showing larger particle diameters.

Behavior of Copper and Sulfur During High-Temperature Sulfurization Of Copper-Smelting Slags with Elemental Sulfur

Behavior of Copper and Sulfur During High-Temperature Sulfurization Of Copper-Smelting Slags with Elemental Sulfur

Photoelectrochemical and Photovoltaic Performance of As-deposited Ink-based CuInS2 Heterojunction Thin Film

In this report, we demonstrate low-temperature ink-based fabrication of CuInS2-based photoelectrodes for hydrogen production capable of producing photocurrent densities as high as 8.8 mA.cm−2. In this process, molecular ink made of metal chlorides and thiourea dissolved in methanol was spin coated onto Mo-coated soda lime glass substrates. Samples were then placed on a hot plate (sample surface temperature: 250 °C) to induce CuInS2 formation and remove the solvent and by-products. No further processing, such as high temperature sulfurization, was performed. The CuInS2 films were then integrated as photocathode for hydrogen evolution by photoelectrodeposition of Pt nanoparticles. Photocurrent density of 0.4 mA.cm−2 at 0 V vs. RHE was detected from such electrodes. However, samples coated with CdS/ZnO/ITO overlayers forming heterojunction prior to Pt deposition exhibited significant improvement of the photocurrent density, reaching 8.8 mA.cm−2 at 0 V vs. RHE, highlighting the improved charge transfer by the p-n junction formed at the CuInS2/CdS interface. The charge transfer resistance of the CuInS2/CdS/ZnO/ITO-Pt photoelectrode was almost 5 times lower than that of the CuInS2-Pt photoelectrode as revealed by electrochemical impedance spectroscopy analysis. In addition, the onset potential was shifted by ca. 0.45 V toward the anodic direction, reaching 0.75 V vs. RHE. Solar cell made of identical structure (Mo/CuInS2/CdS/ZnO/ITO) showed power conversion efficiency of 2.1% with short-circuit photocurrent density and open circuit voltage of 7.4 mA.cm−2 and 820 mV, respectively.

High-temperature sulfur capture by a Mn-Mo sorbent: An investigation of regeneration conditions and SO2 formation and prevention

The regeneration performance of a solid sorbent (alumina-supported 15Mn8Mo) for sulfur capture at high temperature has been studied. The regeneration of the sulfided sorbent was performed by oxidizing at different temperatures (400 – 800 °C) and O2concentrations (0.21 – 21 %). Temperature had a larger impact on the regeneration thanO2concentration. An unwanted side reaction during sulfur capture is SO2formation. Two pathways to SO2formation were identified, either via sulfate formation and decomposition or via oxidation of H2S. A new regeneration method which avoids SO2formation and achieves low residual H2S level in the gas phase involves adding an extra H2pre-reduction step between the regular O2-regeneration and the subsequent sorption step, i.e., a O2– H2regeneration. The stability of the sorbent was verified by 10 repeated sorption/regeneration cycles, with the sorbent regenerated either via the oxidative method or the new O2– H2regeneration method.

Hierarchical wormlike engineering: Self-assembled SnS2 nanoflake arrays decorated on hexagonal FeS2@C nano-spindles enables stable and fast sodium storage

The exploitation of advanced electrode materials with an unique hierarchical architecture and physicochemical feature undertakes an extremely prominent role in achieving rapid ion-transport and remarkable performance to further promote the development of highly efficient sodium-ion batteries (SIBs). Herein, a multi-step synthesis tactic involving in-situ polymerization of dopamine, high-temperature sulfuration and subsequent solvothermal was put forward for the construction of exquisitely hierarchical wormlike architecture by growing SnS2 nanoflake arrays on hexagonal FeS2@C nano-spindles (FeS2@C@SnS2) utilizing tailor-made Fe-based metal–organic framework nanorod as an initial template. The experimental results combined with theoretical analysis thoroughly disclose that the successful construction of the hierarchical wormlike FeS2@C@SnS2 architecture can markedly afford sufficient active reaction sites and favorable Na+ adsorption, as well as accelerate ion-diffusion kinetics and enhance surface-capacitive contribution, thereby synergistically making its higher initial coulombic efficiency, more outstanding cycling capability and rate performance than FeS2@C and SnS2 samples. Specifically, the FeS2@C@SnS2 composite delivers an attractive reversible capacity up to 585.7 mAh g−1 over 1000 cycles at 1.0 A g−1, outstanding high-rate, and durable sodium storage features (only 0.07 % capacity fading each cycle over 2800 cycles at 20.0 A g−1). Moreover, ex-situ experimental characterizations systematically unravel the FeS2@C@SnS2 experiences phase transformations of preliminarily proceeding with the Na+ insertion, followed by the conversion and further alloying-dealloying reaction mechanism. Prompted by the above advantages, the FeS2@C@SnS2||Na3V2(PO4)3@C full cell presents its potential application feasibility toward SIBs, achieving good cycling performance and seductive specific capacity.

Research progress on low-concentration methane oxidation using palladium-based catalysts

There is low concentration (0.05% to 0.5%) of CH4 leakage in marine natural gas engine exhaust. It is difficult to capture and utilize low concentration CH4 because of its stable chemical structure and high ignition temperature. Catalytic oxidation is the main method to remove low concentration CH4 from tail gas. The noble metal palladium (Pd) is the best catalytic material for the complete oxidation of low concentration CH4. In this paper, the main research progress of Pd-based catalysts is reviewed for their low-temperature activity, reliability and development cost. Initially, the impact of Pd particle dimensions and valence distribution, Pd dispersion, carrier identity and strong metal-carrier interaction (SMSI) on the catalyst's methane oxidation activity was elucidated. Then, the mechanism of methane oxidation on the surface of Pdbased catalysts is summarized; In addition, the deactivation mechanisms of Pd-based catalysts, such as high temperature sintering, water poisoning and sulphur poisoning, are described in detail. In conclusion, the major hurdles encountered in achieving full oxidation of methane at low concentrations are outlined, along with the future development direction for methane oxidation catalysts. Additionally, strategies to enhance the performance of Pd-based catalysts are briefly suggested. The modified Text maintains a clear, professional, and concise style with minimal changes.

Cause analysis of corrosion and burst of water wall of utility boiler

During the operation of a boiler in a power plant, the water wall tube burst and leaked. In order to find out the reason of tube rupture, a comprehensive experimental study was made on the sample with macro morphology, chemical composition, metallography, SEM and EDS. The results show that due to the high sulfur content in the combustion medium of the boiler, a large amount of sulfate containing sulfur elements will deposit on the outer wall of the water wall tube during the long-term operation. In the high temperature environment of the boiler, the thermal corrosion of sulfate deposit, that is, high temperature sulphur corrosion, is formed on the side of the water wall wall steel tube, which leads to the continuous thinning of the wall thickness. And finally, explosion leakage occurs under the action of the internal high-temperature and high-pressure medium.

10.3% Efficient Green Cd-Free Cu2 ZnSnS4 Solar Cells Enabled by Liquid-Phase Promoted Grain Growth.

Small grain size and near-horizontal grain boundaries are known to be detrimental to the carrier collection efficiency and device performance of pure-sulfide Cu2 ZnSnS4 (CZTS) solar cells. However, forming large grains spanning the absorber layer while maintaining high electronic quality is challenging particularly for pure sulfide CZTS. Herein, a liquid-phase-assisted grain growth (LGG) model that enables the formation of large grains spanning across the CZTS absorber without compromising the electronic quality is demonstrated. By introducing a Ge-alloyed CZTS nanoparticle layer at the bottom of the sputtered precursor, a Cu-rich and Sn-rich liquid phase forms at the high temperature sulfurization stage, which can effectively remove the detrimental near-horizontal grain boundaries and promote grain growth, thus greatly improving the carrier collection efficiency and reducing nonradiative recombination. The remaining liquid phase layer at the rear interface shows a high work function, acting as an effective hole transport layer. The modified morphology greatly increases the short-circuit current density and fill factor, enabling 10.3% efficient green Cd-free CZTS devices. This work unlocks a grain growth mechanism, advancing the morphology control of sulfide-based kesterite solar cells.

Polymer-directed self-assembly synthesis of tin-titanium-manganese compounded oxides with enhanced activity and sulfur tolerance for NH3-SCR

The majority of NH3-SCR catalysts including MnOx and TiO2-MnOx still exist inferior activity at high temperature, low selectivity, and poor sulfur resistance due to unbefitting redox and adsorption capacities. Novel tin-titanium-manganese compounded oxides catalysts with improved activity and sulfur tolerance are synthesized through a unique polymer-directed self-assembly method for the first time. The reducibility, NH3, and NOx adsorption ability of TiO2-MnOx catalyst are promoted by the incorporation of tin, which contributes to elevating the catalytic activity. More surface chemisorbed oxygen species are formed over Sn-TiO2-MnOx, which is conducive to the generation of NO2, thus shifting the reaction process towards fast NH3-SCR to improve the activity. Moreover, the introduction of Sn could effectively inhibit the electron transfer between SO2 and Mn to suppress the generation of manganese sulfate, thus protecting the active sites. This work develops an enhanced strategy to design an environmental-friendly catalyst with superior catalytic activity and SO2 resistance.

Preparation of functional Ga2S3 and Ga2Se3 shells around Ga2O3 nanowires via sulfurization or selenization

Combining defect semiconductors Ga2S3 and Ga2Se3 in Ga2O3-based heterostructured nanowires (NWs) have potential in photonics and optoelectronics applications due to the materials appealing optical properties. In this work, we have developed and studied Ga2O3–Ga2S3 and, for the first time, Ga2O3–Ga2Se3core-shell NWs. Ga2S3 and Ga2Se3 shell was obtained during high-temperature sulfurization and selenization process of pure Ga2O3 NWs, respectively, in a chemical vapour transport reactor. As-grown nanostructures were characterized with scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and photoluminescence measurements. Single-nanowire photodetector devices were fabricated in order to demonstrate their electric and photoconductive properties. Such novel core-shell NW heterostructures could potentially be used in next-generation nanoscale electronic and optoelectronic devices.

High-temperature sulfurized synthesis of MnxCd1-xS composites for enhancing solar-light driven H2 evolution

In recent years, tremendous efforts have been devoted to develop new photocatalyst with wide spectrum response for H 2 generation from water or aqueous solution. In this paper, Mn x Cd 1-x S composites were in-situ fabricated via the high-temperature sulfurization to enhance the solar-light photocatalytic capacity of H 2 evolution. Benefiting from the S defects and junction interface between MnS and CdS, Mn x Cd 1-x S composites exhibited the better H 2 evolution rate than pure MnS. The H 2 evolution rate of optimal Mn 0.5 Cd 0.5 S with a Mn(II) content of 22.52% and a Mn/Cd mole ratio of 0.95:1 was 9.27 mmol g −1 h −1 , which was 35.65 and 2.38 times higher than pure MnS (0.26 mmol g −1 h −1 ) and CdS (3.89 mmol g −1 h −1 ), respectively. In addition, H 2 evolution capacity of Mn 0.5 Cd 0.5 S decreased from 44.83 to 41.66 mmol g −1 after three cycles. Mn 0.5 Cd 0.5 S prepared via the high-temperature sulfurization was thus a potential material for solar-light induced H 2 generation. • Mn x Cd 1-x S composites were prepared via High-temperature sulfurized route. • Mn x Cd 1-x S composites exhibit the excellent solar light driven H 2 evolution. • S vacancies of Mn x Cd 1-x S serve as the efficient active sites for H 2 evolution reaction.

Proposing a suitable slag composition by estimating the fusion behavior, viscosity and desulphurization ability for blast furnaces running with high alumina

The present work was focused on identifying a suitable quaternary CaO-MgO-SiO2-Al2O3 high alumina slag for blast furnaces running with high alumina ores as an input raw material. These high alumina slags have inferior properties like high liquidus temperature, high viscosity and poor sulphur absorption capacity. These properties will hamper the working condition of the blast furnace as well as quality of hot metal produced. To overcome these issues, it is necessary to focus on selecting an appropriate slag composition having superior properties like, minimum difference between softening and flow temperature (ST & FT) (<100 °C), low liquidus temperature, good fluidity (i.e. viscosity <0.6 pas. at 1773 K) & high sulphur absorption capacity at 1773 K. In the current work various slag compositions having Al2O3 25–30 %, CaO/SiO2 ratio (0.8–1.6), and MgO (8–16 %) has considered for determining fusion temperature, viscosity and desulphurization ability of slag using high temperature microscope, viscometer and slag-metal Desulphurization experiments. It was found that slag with Al2O3 (30 %) and C/S ratio (1.2) coupled with MgO (12 %) is showing superior properties like low FT-ST (i.e. short slag) having viscosity 0.35 pas and Desulphurization ability of approx. 80 % at 1773 K which fulfills the necessary conditions for better working condition of the blast furnace.

Rational design of the FeS2/NiS2heterojunction interface structure to enhance the oxygen electrocatalytic performance for zinc–air batteries

The zinc–air battery with FeS2/NiS2HDSNRs prepared by a one-step hydrothermal self-template process and high-temperature sulfurization process exhibits long-term stability for 480 h, and was well observed byin situXRD.

Investigation on the corrosion behavior of Ni-Cr-Mo-W-xSi laser cladding coating in H2S corrosion environment

Ni-Cr-Mo-W-xSi laser cladding coating with Si mass fraction changing from 0, 1 wt .%, 3 wt .% to 5 wt .% were fabricated by laser cladding technology. The influence of Si content on the phase constitution, microstructure evolution and high temperature sulfur corrosion resistance were investigated. Experimental results showed that the order of corrosion resistance under H2S corrosion environment at 500-600℃ was S1 > S0 > S3 > S5. The optimized content of Si addition for Ni-Cr-Mo-W-xSi laser cladding coating is 1 wt% due to the benefit of enrichment of Mo and Cr in the inner layer resulting in a protective oxides scale and better corrosion resistance while excessive Si (1% < Si ≤ 5%) caused obvious cracks along the network grain boundaries leading to poor corrosion resistance. Corrosion products such as NiS, Cr2S3, MoO2 and other mixed corrosion products were detected and the multi-layer structure of corrosion scales were observed. The formation of outermost sulfide layer and innermost oxide layer was duo to the corrosion of Ni and Mo leading to a selective formation of Ni-S and Mo-O, respectively. The detailed corrosion mechanisms based on the Gibbs free energy principle were discussed in this study.