A thermodynamic view on the in-situ carbon dioxide reduction by biomass-derived hydrogen during calcium carbonate decomposition

In the carbonate industry,deep decarbonization strategies are necessary to effectively remediate CO_(2).These strategies mainly include both sustainable energy supplies and the conversion of CO_(2)in downstream processes.This study developed a coupled process of biomass chemical looping H2 production and reductive calcination of CaCO_(3).Firstly,a mass and energy balance of the coupled process was established in Aspen Plus.Following this,process optimization and energy integration were implemented to provide optimized operation conditions.Lastly,a life cycle assessment was carried out to assess the carbon footprint of the coupled process.Results reveal that the decomposition temperature of CaCO_(3)in an H_(2)atmosphere can be reduced to 780℃(generally around 900℃),and the conversion of CO_(2)from CaCO_(3)decomposition reached 81.33%with an H2:CO ratio of 2.49 in gaseous products.By optimizing systemic energy through heat integration,an energy efficiency of 86.30%was achieved.Additionally,the carbon footprint analysis revealed that the process with energy integration had a low global warming potential(GWP)of-2.624 kg·kg^(-1)(CO_(2)/CaO).Conclusively,this work performed a systematic analysis of introducing biomass-derived H_(2)into CaCO_(3)calcination and demonstrated the positive role of reductive calcination using green H_(2)in mitigating CO_(2)emissions within the carbonate industry.

Chemical Reduction of CO_2 to Different Products during Photo Catalytic Reaction on TiO_2 under Diverse Conditions:an Overview

The chemical reduction of CO2 remains a challenge with respect to the reversal of the oxidative degradation of any organic materials. The conversion of CO2 into useful substances is essential in developing alternative fuels and various raw materials for different industries. This also aids in preventing the continuous rise in tropospheric temperature due to the green house effect of CO2. In this article an overview of the growth taken place so far in the field of CO2 chemical reduction is pre- sented. The discussion comprises of photochemical methods for the development of different products, viz. CO, CH3OH and CH4, through chemical reduction of CO2. This includes the use of photo catalysts, mainly TiO2, and the role of a hole scavenger （such as 2-propanol） for this purpose.

Preparation of copper nanoparticles by chemical reduction method using potassium borohydride

High dispersive copper nanoparticles were prepared by chemical reduction method using potassium borohydride as reducing agent.The effects of reactant ratio,concentration of CuSO4,reaction temperature,and dispersant on the size of product and conversion rate were studied.The morphologies of copper nanoparticles were characterized by scanning electron microscopy.The results show that the optimum process conditions are as follows:the molar ratio of KBH4 to CuSO4 is 0.75(3:4),concentration of CuSO4 is 0.4 mol/L,reaction temperature is 30℃,and dispersant is n-butyl alcohol.The average particles size of copper powders with spherical shape gained is about 100 nm.

Recent advances on the reduction of CO2 to important C2+ oxygenated chemicals and fuels

The chemical utilization of CO_2 is a crucial step for the recycling of carbon resource. In recent years, the study on the conversion of CO_2 into a wide variety of C_(2+) important chemicals and fuels has received considerable attention as an emerging technology. Since CO_2 is thermodynamically stable and kinetically inert, the effective activation of CO_2 molecule for the selective transformation to target products still remains a challenge. The welldesigned CO_2 reduction route and efficient catalyst system has imposed the feasibility of CO_2 conversion into C_(2+) chemicals and fuels. In this paper, we have reviewed the recent advances on chemical conversion of CO_2 into C_(2+) chemicals and fuels with wide practical applications, including important alcohols, acetic acid, dimethyl ether, olefins and gasoline. In particular, the synthetic routes for C\\C coupling and carbon chain growth, multifunctional catalyst design and reaction mechanisms are exclusively emphasized.

Microwave enhanced chemical reduction process for nitrite-containing wastewater treatment using sulfaminic acid

High-concentration nitrite-containing wastewater that presents extreme toxicity to human health and organisms is difficult to be treated using traditional biological process. In this study, a novel microwave-enhanced chemical reduction process （MECRP） using sulfarninic acid （SA） was proposed as a new manner to treat such type of wastewater. Based on lab-scale experiments, it was shown that 75%-80% nitrite （NO2-） could be removed within time as short as 4 min under 50 W microwave irradiation in pH range 5-10 when molar ratio of SA to nitrite （SA/NO2-） was 0.8. Pilot-scale investigations demonstrated that MECRP was able to achieve nitrite and chemical oxygen demand （COD） removal with efficiency up to 80% and 20%, respectively under operating conditions of SA concentration 80 kg/m3, SA/NO2- ratio 0.8, microwave power 3.4 kW, and stirring time 3 min. Five-day biological oxygen demand （BODs）/COD value of treated effluent after MECRP was increased from 0.05 to 0.36 （by 620%）, which clearly suggested a considerable improvement of biodegradability for subsequent biological treatment. This study provided a demonstration of using microwave irradiation to enhance reaction between SA and nitrite in a short time, in which nitrite in wastewater was completely converted into nitrogen gas without leaving any sludge and secondary pollutants.

Fischer–Tropsch synthesis using Co and Co-Ru bifunctional nanocatalyst supported on carbon nanotube prepared via chemical reduction method

We used a chemical reduction method to synthesize the catalysts of cobalt(Co) and cobalt-ruthenium(Co-Ru) bifunctional supported on carbon nanotubes(CNTs) for Fischer–Tropsch synthesis(FTS) in a fixedbed reactor. These Co-Ru/CNTs catalysts were synthesized with various weight proportions of Ru/Co(0.1 to 0.4 wt%) with keeping a fixed amount of cobalt(10 wt%). Moreover, for comparison purpose, CNTs supported Co-and Co(Ru)-based catalysts at same loading as the above catalysts were prepared through impregnation method. We characterize the present catalysts through the various techniques such as Energy–dispersive X-ray(EDX), Transmission Electron Microscopy(TEM), Brunauer–Emmett–Teller(BET),Hydrogen-Temperature-Programmed Reduction(H_2-TPR), Hydrogen-Temperature-Programmed Desorption(H_2-TPD) and O_2 titration. Thus using the chemical reduction method, a narrow particle size distribution was obtained so that the small cobalt particles were confined inside the CNTs. The Co-based catalyst prepared by impregnation was compared with the Co-Ru catalysts at the same loading. The results demonstrated that the use of chemical reduction method led to decrease the average Co oxide cluster size to8.7 nm so that the reduction enhanced about 24% and stabilized an earlier time at the stream. Among the prepared catalysts, the results indicated that the Co-Ru/CNTs catalysts demonstrated high catalytic activity with the highest long-chain hydrocarbons(C_(5+)), selectivity up to 74.76%, which was higher than those we obtained by the Co-Ru/γ-Al_2O_3(61._20%), Co/CNTs(43.68%) and Co/γ-Al_2O_3(37.69%). At the same time, comparing with those catalyst synthesized by impregnation, the use of chemical reduction led to enhancement of the C_(5+) selectivity from 59.30% to 68.83% and increment in FTS rate about 11% for the Co-Ru/CNTs catalyst.

Effects of surface chemical properties of activated coke on selective catalytic reduction of NO with NH_3 over commercial coal-based activated coke

Surface chemical properties of typical commercial coal-based activated cokes were characterized by Xray photoelectron spectroscopy(XPS) and acid-base titration, and then the influence of surface chemical properties on catalytic performance of activated cokes of NO reduction with NH3 was investigated in a fixed-bed quartz micro reactor at 150 ℃. The results indicate that the selective catalytic reduction(SCR) activity of activated cokes with the increase of its surface acidic sites and oxygen content,obviously, a correlation between catalytic activity and surface acidic sites content by titration has higher linearity than catalytic activity and surface oxygen content by XPS. While basic sites content by acid-base titration have not correlation with SCR activity. It has been proposed that surface basic sites content measured by titration may not be on adjacent of acidic surface oxides and then cannot form of NO2-like species, thus the reaction of reduction of NO with NH3 have been retarded.

Atomic Level Dispersed Metal–Nitrogen–Carbon Catalyst toward Oxygen Reduction Reaction: Synthesis Strategies and Chemical Environmental Regulation

For development and application of proton exchange membrane fuel cell(PEMFC) energy transformation technology, the cost performance must be elevated for the catalyst. At present, compared with noble metal-based catalysts, such as Pt-based catalysts, atomically dispersed metal–nitrogen–carbon(M–N–C) catalysts are popularity and show great potential in maximizing active site density, high atom utilization and high activity,making them the first choice to replace Pt-based catalysts. In the preparation of atomically dispersed metal–nitrogen–carbon catalyst, it is difficult to ensure that all active sites are uniformly dispersed, and the structure system of the active sites is not optimal. Based on this, we focus on various approaches for preparing M–N–C catalysts that are conducive to atomic dispersion, and the influence of the chemical environmental regulation of atoms on the catalytic sites in different catalysts. Therefore, we discuss the chemical environmental regulation of the catalytic sites by bimetals, atom clusters, and heteroatoms(B, S, and P). The active sites of M–N–C catalysts are explored in depth from the synthesis and characterization, reaction mechanisms, and density functional theory(DFT)calculations. Finally, the existing problems and development prospects of the current atomic dispersion M–N–C catalyst are proposed in detail.

Chemical Fertilizer Reduction and High Yield Cultivation Technique for Peanut

For a long time,the amount of fertilizer applied to peanuts in China has been much higher than that of other main peanut producing countries.At the same time of increasing production,chemical fertilizers have also brought many adverse effects,which have brought potential threats to the sustainable development of peanut production.While continuously increasing the yield,reducing the amount of chemical fertilizer has become an urgent problem to be solved in peanut production of China.Based on the research results of our team,this paper appropriately absorbed the latest research progress of chemical fertilizer reduction in related fields,and established the cultivation technique for peanut fertilizer reduction and high yield under different cultivation modes,to realize the synchronization of fertilizer reduction and yield increase for peanut production.The technique includes two parts:common technology and different cultivation mode fertilization schemes.The former includes crop rotation,proper deep tillage,application of organic fertilizer,selection of nutrient-efficient varieties,topdressing of foliar fertilizer,etc.,the latter includes film mulching spring peanut,continuous cropping field,acidified soil,peanuts interplanting with wheat,and summer direct sowing,etc.This technique provides a technical support for the chemical fertilizer reduction of peanut production in China.

Size-dependent melting properties of Sn nanoparticles by chemical reduction synthesis

Tin nanoparticles with different size distribution were synthesized using chemical reduction method by applying NaBH4 as reduction agent.The Sn nanoparticles smaller than 100 nm were less agglomerated and no obviously oxidized.The melting properties of these synthesized nanoparticles were studied by differential scanning calorimetry.The melting temperatures of Sn nanoparticles in diameter of 81,40,36 and 34 nm were 226.1,221.8,221.1 and 219.5？欲espectively.The size-dependent melting temperature and size-dependent latent heat of fusion have been observed.The size-dependent melting properties of tin nanoparticles in this study were also comparatively analyzed by employing different size-dependent theoretical melting models and the differences between these models were discussed.The results show that the experimental data are in accordance with the LSM model and SPI model,and the LSM model gives the better understanding for the melting property of the Sn nanoparticles.

Synthesis of Cu nanoparticles by chemical reduction method

Cu nanoparticles (CuNPs) have been synthesized through an easy route by chemical reduction at room temperature. The Cu^2+ ions were reduced and stabilized with sodium borohydride and polyvinylpyrrolidone, respectively. The effect of the variation of the reducing agent/precursor-salt (RA/PS) ratio on the size and morphology of the CuNPs was evaluated. The synthesized material was studied by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The UV-Vis spectra showed a CuNPs plasmon peak at 569 nm and another peak belonging to Cu2O at 485 nm. XRD analysis showed the fcc-Cu phase with a small amount of fcc-Cu2O compound. SEM and TEM studies displayed that small semispherical CuNPs of approximately 7 nm were obtained at the RA/PS ratio of 2.6. The excess of polyvinylpyrrolidone stabilizer played an essential role in preventing CuNPs oxidation. On the other side, Cu2O polyhedral particles with larger sizes up to 150 nm were identified in the RA/PS ratio range of 2.0-1.84. In addition, Cu2O particles having star morphologies with quantum confinement at their tips were obtained at the RA/PS ratio of 1.66.

Numerical simulation of chemical vapor deposition reaction in polysilicon reduction furnace

Three-dimensional model of chemical vapor deposition reaction in polysilicon reduction furnace was established by considering mass, momentum and energy transfer simultaneously. Then, CFD software was used to simulate the flow, heat transfer and chemical reaction process in reduction furnace and to analyze the change law of deposition characteristic along with the H_2 mole fraction, silicon rod height and silicon rod diameter. The results show that with the increase of H_2 mole fraction, silicon growth rate increases firstly and then decreases. On the contrary, SiHCl_3 conversion rate and unit energy consumption decrease firstly and then increase. Silicon production rate increases constantly. The optimal H_2 mole fraction is 0.8-0.85. With the growth of silicon rod height, Si HCl3 conversion rate, silicon production rate and silicon growth rate increase, while unit energy consumption decreases. In terms of chemical reaction, the higher the silicon rod is, the better the performance is. In the view of the top-heavy situation, the actual silicon rod height is limited to be below 3 m. With the increase of silicon rod diameter, silicon growth rate decreases firstly and then increases. Besides, SiHCl_3 conversion rate and silicon production rate increase, while unit energy consumption first decreases sharply, then becomes steady. In practice, the bigger silicon rod diameter is more suitable. The optimal silicon rod diameter must be over 120 mm.

Fabrication and Characterization of Tungsten Heavy Alloys Using Chemical Reduction and Mechanical Alloying Methods

A novel reduction technique has been developed to synthesize nano-sized tungsten heavy alloys powders and compared with the same powders processed by mechanical alloying technique. In the first method, nano-sized tungsten heavy alloys powders have been obtained by reduction of precursors obtained by spray drying of several appropriate aqueous solutions, which were made from salts containing tungsten, cobalt, and nickel. By adjusting the stoichiometry of the component of the solutions, it is possible to obtain the desired chemical composition of the tungsten heavy alloys powders. In the second method, highly pure elemental powders of tungsten heavy alloys have been mechanically alloyed in a tumbler ball mill for different milling time. The investigated tungsten heavy alloy powders with the composition (95%W-3.5%Ni-1.5%Fe), (93%W-4.5%Ni-1.0%Fe-1.5%Co), and (90%W-6%Ni-4%Cu) have been prepared using both methods. The prepared powders have been compacted at 70 bar (200 MPa) and sintered in vacuum furnace at 1400℃. Vacuum sintering was carried out to achieve full densification of the produced tungsten heavy alloys. The investigated materials were going to be evaluated the physical and mechanical properties of the sintered parts such as density;electrical conductivity, hardness, and transverse rupture strength. The results reveal that, the grain size of alloys fabricated by chemical reduction technique (53.1 - 63.8 nm) is smaller than that fabricated by mechanical alloying technique (56.4 - 71.4 nm).

Investigation of Fe-Ni-B and Fe-Cr-B Ultrafine Amorphous Alloy Powders Prepared by Chemical Reduction

Ultrafine amorphous alloy powders of spherical shape with diameters from 10 to 50nm for Fe-Ni-B and Fe-Cr-B were prepared by chemical reduction. The amorphous structure of two powders was identified by X-ray diffraction. The B concentrations for the two alloy systems did not change dramatically, as the preparation condition changed. An oxide film covered up the powders. The maximum magnetization decreased as increasing the content of Ni or Cr.

The Preparation of Nano Silver by Chemical Reduction Method

A silver nanostructures prepared by using chemical reduction method. The silver nanoparticles were prepared with diameters of about (20 nm). Numerous techniques had been used to study the optical, structural like the UV-Vis absorption spectrometer, Ttransmission Electron Microscopy (TEM), Field-Emission Scanning Electron microscope (FESEM), and X-ray diffraction (XRD). The practical results exhibited the absorption spectrum of the prepared nanoparticles at (357 nm), it was found that there is a relationship between the positions of the optical absorption peak and the size of the silver nanoparticles. The analysis of TEM results showed the presence of nanoparticles in the range (20 nm). The analyzing of XRD results explained the crystal structure for silver nanoparticles. It is found a cubic unit cell have a lattice constants (a = 4.0855 Å), with the Miller indices were (111), (002), (002), and (113).

Synthesis of Sn-3.5Ag Alloy Nanosolder by Chemical Reduction Method

The synthesis of Sn-3.5Ag alloy nanosolder was investigated by chemical reduction method. In this method, chemical precipitation was achieved by using sodium NaBH4 as a reducing agent and PVP (poly-m-vinyl 2- pyrrolidone) as a stabilizer. The experimental results obtained with different amounts of NaBH4 and PVP were compared. X-ray diffraction (XRD) patterns revealed that Ag3Sn was formed due to the successful alloying process. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) demonstrated a change in the morphology of Sn-3.5 Ag alloy nanosolder with increase in the PVP content in the bath. The size of the nanoparticles ranged from 300 to 700 nm. The nanosolder/nanoparticles were thus synthesized successfully under controlled and optimized chemical reduction process.

Fe3O4 and Fe Nanoparticles by Chemical Reduction of Fe(acac)3 by Ascorbic Acid: Role of Water

Nanoparticles of Fe3O4 and Fe are chemically synthesized by reduction of Fe(acac)3 using ascorbic acid in controlled condition. It was observed that addition of water during the chemical synthesis process yields Fe3O4 nanoparticles, whereas if the reaction is carried out in absence of water yields Fe nanoparticles—which get oxidized upon exposure to air atmosphere. Fe3O4 (15 ± 5 nm) and Fe/iron oxide nanoparticles (7 ± 1 nm) were successfully synthesized in the comparative study reported herewith. Mechanism for formation/synthesis of Fe3O4 and Fe/iron oxide nanoparticles is proposed herewith in which added water acts as an oxygen supplier. Physico-chemical characterization done by SEM, TEM, EDAX, and XPS supports the proposed mechanism.

稠油化学复合冷采技术研究与应用

我国稠油储量可观,其中60%的是深层稠油,而主流的蒸汽吞吐等热采技术采收率不足20%;稠油资源开发潜力极大,积极探索新的开采方式以提高采收率是石油领域高质量发展的必然选择。本文着重阐述稠油化学复合冷采技术体系构建及其现场应用,为中深层稠油的新型绿色低成本接替技术发展提供有效方案。在分析稠油组分的基础上,细致剖析稠油结构致黏机理,包括化学降黏机理、降低启动压力梯度机理、提高驱油效果机理在内的提高采收率机理,以丰富理论认识。面向工程应用亟需,从水溶性降黏剂分子设计与合成、自组装调堵剂研发两方面出发,突破稠油绿色化学驱油体系。基于发展的稠油化学复合冷采技术,完成了3个稠油油田示范工程应用,在提高产油量、控制含水率方面取得了良好成效。进一步梳理了分子采油理论与技术、渗流理论与数值模拟技术等方面的后续发展要点,以为深层稠油的绿色高效开发接替技术研究、稠油化学复合冷采技术推广应用研究等提供启发和参考。

化肥减施下不同生物质炭对大棚辣椒生长及产量品质的影响

通过田间试验,考察化肥减施条件下两种小麦秸秆生物质炭在辣椒生产上的应用效果。结果表明,在氮磷钾总养分量减少30%以上的条件下,生物质炭1号(T1)、生物质炭2号(T2)均可明显改善土壤理化性质,提高大棚辣椒的产量与品质。与不施生物质炭(CK)相比,T1和T2处理的土壤有机质含量分别提高了15.57%和30.54%,辣椒产量分别提高了16.28%和12.66%,差异均显著;T1处理辣椒果实干物质、VC含量均最高,T2处理的可溶性糖、蛋白质含量均最高。综合对比两种生物质炭施肥处理效果,T1处理促进辣椒增产的效果较好,T2处理提升辣椒品质的效果较好。

化工冶金跨行业耦合二氧化碳循环利用技术

双碳战略是国家重大战略,也是推动国家经济高质量可持续发展的必由之路。我国碳达峰到碳中和时间短、任务重。我国化工冶金每年碳排放约36亿t,约占全国工业碳排放量的36%,此外化工冶金废气、固废、废热产生量大、堆存量多、难利用、循环利用率低。发展化工冶金低碳化转型和变革,是我国工业领域双碳目标实现的根本保证。我国化工冶金历时百年,已发展成熟,仅通过原料燃料替代及绿色工艺转型减碳容量有限,亟需开展化工冶金跨行业耦合与循环利用技术变革,深入推动工业领域减碳。我国化工冶金大多是孤立、非循环连续工艺过程,引起跨行业耦合难、循环利用难度大的问题。针对上述问题,首先分析了化工冶金行业碳排放治理现状及国家战略需求;其次,提出了废气与废热耦合热化学转化制高质气体、废气与废气耦合定向催化制高端化学品、废气与固废耦合制低碳材料3个减碳增效策略。结合其技术发展现状和趋势,提出了拟重点发展的化工冶金跨行业耦合二氧化碳循环利用技术,以期为工业低碳绿色发展提供支撑。