真空紫外光化学反应器的研究

设计了能产生波长小于200 nm的真空紫外光化学反应器,通过工作气体氮气进行光强标定表明,其主要产生109 nm,120 nm,149 nm,174 nm波长的光(N原子谱线)。首次在该光化学反应器中进行了CO2光解反应的研究,实验结果表明该实验条件下CO2光解后生成产物CO,当光源电流300 mA时,生成CO的相对量与光源内工作气体的真空度相关。提出了光化学反应器设计时存在的问题、影响因素及考虑因素,为光化学反应器设计放大和操作条件优化提供实验依据和理论思路。     

超重力法脱除变换气中的CO2

用N2和CO2的混合气体模拟变换气,采用苯菲尔溶液为吸收液进行了超重力法脱除CO2的实验研究,考察了反应温度、系统压力、超重力水平、气液比对反应器出口CO2含量的影响。实验结果表明:随着温度的升高和超重力水平的增强,反应器出口CO2含量先降后升;随着压力的升高,反应器出口CO2含量逐渐降低;液体流量一定时,随着气液比的增大,反应器出口CO2含量逐渐升高。     

CO2介质中离子液体催化苯与1-十二烯烃连续式反应

为了解决离子液体催化苯与长链烯烃连续式反应中离子液体相与反应液相互溶性差的问题,在[Bmim]Br-AlCl3催化苯与1-十二烯烃连续式反应中引入了CO2作为反应介质,并考察了CO2-苯-1-十二烷基苯-[Bmim]Br-AlCl3四元物系的相平衡和CO2压力、温度、空时和苯烯比对烷基化反应的影响。结果表明,在30-60℃,7．90-8．10MPa的条件下,反应物在离子液体相与反应液相浓度分布均一,有利于提高烯烃的转化率。提高苯烯比对改善单取代烷基苯产率的作用明显。在60℃,8．10MPa和空时为2min的条件下,苯烯物质的量之比为2时,单取代十二烷基苯产率最高为59．2％,苯烯物质的量之比为12时,单取代烷基苯的产率为85．9％。     

光转换薄膜用碳量子点的合成及其发光性能

开展了光转换薄膜用碳量子点的合成及其发光性能研究,着重探讨了氮(N)源种类对碳量子点发光性能的影响。结果表明,以尿素为N源时,合成出发射峰值位于440～530 nm范围的具有不同颜色特征的碳量子点。而以二乙烯三胺为N源时,合成出发射峰值位于450～460 nm的蓝光N掺杂碳量子点;随着激发波长的增大,碳量子点的发射光谱产生红移。采用不同N源时所合成碳量子点的发光特性差异,主要源于碳量子点晶粒尺寸的不同和表面官能团的化学修饰作用,后者填补了碳量子点的表面缺陷、或使碳量子点的带隙产生了差异,进而导致了不同的发光特性。     

一种UVA型光产酸剂

本文合成了一种以硫杂蒽酮为基核的光产酸剂,该光产酸剂对UVA段紫外光敏感,光解可以产生超强酸,且在365、385、395 nm LED光源下具有良好的光产酸效率,光产酸量子产率Φa为0.10～0.11。     

金属醋酸盐复配催化剂催化超临界CO2一步法合成碳酸二甲酯

由CO2合成碳酸二甲酯(DMC)是CO2资源化的重要途径之一。超临界CO2因具有独特的溶解和传递性能,在合成反应中可既作反应物,又作反应溶剂。本实验以超临界CO2、环氧丙烷和甲醇作为反应物,选用金属醋酸盐与K2CO3、KI复合催化一步合成DMC。在温度130~170℃、CO2压力2~14 MPa条件下,考察了催化剂用量、物料配比、温度、压力、反应时间等条件对DMC产率的影响,产物采用气相色谱以内标法进行定量分析。结果表明,当醋酸锌复合催化剂配比为K2CO3:KI:Zn(CH3COO)2=1:1:2时,在合适的反应条件下(催化剂用量4%,物料配比8:1,160℃、7.4MPa,反应4 h),环氧丙烷转化率可达95%,DMC产率可达54.3%。     

基于Er3+/Yb3+掺杂的上转换玻璃陶瓷材料的制备和性能

采用熔融-晶化法在ZnO-Al2 O3-SiO2系玻璃陶瓷的基础上,用GeO2取代部分SiO2成功制备出Er3+/Yb3+共掺ZnO-Al2 O3-GeO2-SiO2系玻璃陶瓷,并通过对样品的硬度及上转换荧光测试分析确定了GeO2的最佳取代量为7.5wt％.研究发现在980 nm波长光的激发下,样品产生了绿色(524 nm、546 nm)和红色(659 nm)上转换发光,且当Er3+/Yb3+掺杂比为2.5:6.5时样品上转换荧光强度最强.     

阿维菌素光化学降解研究及其光稳定剂的筛选

研究了光源波长、光照强度以及阿维菌素初始浓度对其光降解的影响,并系统考察了紫外吸收剂阿凡达、抗氧化剂BHT、光屏蔽剂纳米SiO_2和表面活性剂十二烷基硫酸钠对阿维菌素光降解的影响。结果表明:光源波长越短,光照强度越大,初始浓度越低,则阿维菌素的光解速率越高。紫外吸收剂、抗氧化剂及光屏蔽剂对阿维菌素光降解有显著抑制作用。     

钨酸钆镉单晶的光致发光性能

采用提拉法生长了钨酸钆镉[CdGd2(WO4)4, CGW]单晶.在室温下测试和研究了CGW单晶的光致发光谱和X射线能量色散谱.结果表明:样品中有Gd,Cd,W和O元素,未见其他杂质元素;样品的发光性质随激发波长的不同而有所变化.在313 nm波长光激发下,有3个发光带,分别为447 nm蓝光,487 nm蓝绿光和545 nm绿光;在353 nm波长光激发下,不仅有蓝光、蓝绿光和绿光出现,另外出现了575 nm黄光发光峰;在367 nm波长的光激发下,出现775 nm红光发光峰.对发光机制分析认为:蓝光和蓝绿光为本征发射,起源于WO42-离子团的内部电子跃迁;绿光起源于"WO42- Oi";黄光和红光起源于WO3内部跃迁.     

N2气氛下温度和压力对煤热解的影响

研究煤热解的反应特性有助于提高煤热解的转化率和焦油收率并且能够改善焦油的品质。本文在固定床反应器上研究了N₂气氛中,不同压力和温度下的唐山烟煤热解反应,考察了温度和压力对热解失重率、热解气体组成及液相产物产率的影响规律。结果表明当热解压力由1MPa增加至3MPa时,唐山烟煤的失重率和焦油产率均先增加后降低,在2MPa时达到最大值。当温度低于600℃时,压力不影响CH₄、H₂和CO的收率,当温度超过600℃时,CH₄、H₂和CO的收率随热解压力的升高而降低。随着热解温度的升高,煤热解的失重率、水的产率以及CH₄、H₂的收率不断增大,焦油的收率和CO的收率先增大后降低,在2MPa下600℃时焦油的收率达最大值为9.23%。     

Investigation of carbon dioxide photoreduction process in a laboratory-scale photoreactor by computational fluid dynamic and reaction kinetic modeling

The production of solar fuels via the photoreduction of carbon dioxide to methane by titanium oxide is a promising process to control greenhouse gas emissions and provide alternative renewable fuels. Although several reaction mechanisms have been proposed, the detailed steps are still ambiguous, and the limiting factors are not well defined. To improve our understanding of the mechanisms of carbon dioxide photoreduction, a multiphysics model was developed using COMSOL. The novelty of this work is the computational fluid dynamic model combined with the novel carbon dioxide photoreduction intrinsic reaction kinetic model, which was built based on three-steps, namely gas adsorption, surface reactions and desorption, while the ultraviolet light intensity distribution was simulated by the Gaussian distribution model and Beer-Lambert model. The carbon dioxide photoreduction process conducted in a laboratory-scale reactor under different carbon dioxide and water moisture partial pressures was then modeled based on the intrinsic kinetic model. It was found that the simulation results for methane, carbon monoxide and hydrogen yield match the experiments in the concentration range of 10⁻⁴ mol·m^–3 at the low carbon dioxide and water moisture partial pressure. Finally, the factors of adsorption site concentration, adsorption equilibrium constant, ultraviolet light intensity and temperature were evaluated.     

New continuous gas-phase synthesis of high purity carbon nanotubes by a thermal plasma jet

We have developed a new gas-phase synthesis technique to produce carbon nanotubes (CNTs) with a continuous process and at high temperature, by using a thermal plasma jet. A thermal plasma jet was generated by applying a direct current of 100-300 A, using Ar as the plasma gas with a flow rate of ∼6 ksccm. The temperature of the thermal plasma jet was very high (∼10⁴ K) and the velocity was very fast (∼100 m/s). Fe(CO)₅ and CO were used as a catalyst precursor and carbon source, respectively. The yield of CNTs was dramatically increased by attaching a helical extension reactor at the end of the plasma nozzle. High purity (∼80%) CNTs were produced with a continuous process by using a thermal plasma jet with helical extension reactor equipment. The number of CNT walls produced was critically affected by the hydrogen gas injected as an auxiliary plasma gas. Without hydrogen gas, single-walled carbon nanotubes whose diameter was about 1 nm were mostly produced while with hydrogen gas double-walled carbon nanotubes (about 4 nm in diameter) were predominantly produced, with small amount of 3- and 4-walled carbon nanotubes.     

浆态床中二氧化碳加氢合成甲醇

研究了浆态床中自行开发的LP201甲醇合成催化剂上二氧化碳加氢合成甲醇的过程。探讨了不同操作条件,如温度、压力、气体空速、原料气配比等对反应的影响;考察了该催化剂在浆态床二氧化碳加氢合成甲醇过程中的稳定性。实验结果表明,浆态床二氧化碳加氢合成甲醇过程中主要产物为甲醇、CO和水;随温度的增加,CO2的转化率和甲醇产率呈现上升的趋势,但甲醇的选择性明显下降;压力的升高有利于CO2的转化率、甲醇产率以及甲醇的选择性提高;原料气空速的提高会增大甲醇产率,但同时降低CO2的转化率以及甲醇的选择性;CO2的转化率、甲醇收率以及甲醇的选择性在氢碳摩尔比4～5获得极大值。LP201催化剂的寿命考察结果表明,该催化剂具有较好的催化活性和稳定性。     

Reactions of benzene in a microwave discharge reactor

A study has been made of the reactions of benzene in a continuous-flow microwave-discharge reactor. The distribution of reaction products was found to depend on the reactor pressure and flow-rate. By accounting for all reaction products (solid, liquid and gas) an overall mass balance was obtained. The reactions are not the result of simple pyrolysis. The insertion of nickel wire into the reactor enhanced the reactions which proceed via a radical—radical mechanism. The addition of carbon dioxide to the benzene feed appeared to retard reactions which involve highly energetic ionisation processes. Thus, the presence of carbon dioxide changed the reaction selectivity. The carbon dioxide did not react chemically. Comparison with other work with benzene shows that the behaviour of this reactor system is significantly different from the behaviour of reactors which operate at a lower frequency. It is suggested that the distribution of electron energies in the microwave discharge is narrower than the energy distributions which are encountered in lower-frequency and d.c. discharges.     

Biomass gasification using capacitively coupled RF plasma technology

A laboratory-scale capacitively coupled radio frequency (RF) plasma pyrolysis reactor working in reduced pressure has been developed. Experiments have been performed to examine the characteristics of this RF plasma reactor and the products of biomass gasification. It was found that the electrode geometry, input power and reactor pressure were the key parameters affecting the plasma characteristics such as plasma length, temperature, and energy transfer efficiency. Biomass gasification using input power 1600-2000 W and reactor pressure 3000-8000 Pa produced a combustible gas consisted of H₂, CO, CH₄, CO₂ and light hydrocarbons as well as a pyrolytic char. On average, the gas yield can reach 66 wt% of the biomass feed. An energy balance analysis on the RF plasma pyrolysis system was also given.     

Reactions of cyclohexane in a microwave discharge reactor

A study has been made of the reactions of cyclohexane in a continuous-flow microwave discharge reactor. Butene-1 and propylene were the major reaction products; ethylene and hydrogen were produced in smaller amounts. The distribution of reaction products was found to depend on the reactor pressure and flow-rate. The results show that the fragmentation of cyclohexane is not the sole source of butene-1. The insertion of nickel wire into the reactor enhanced the production of ethylene and propylene; yields of butene-1 were diminished. In the presence of nickel the production of ethylene and propylene became independent of pressure. When carbon dioxide was added to the cyclohexane feed the major reaction product was acetylene. The carbon dioxide did not react chemically. The yields of acetylene per unit energy input were found to be fairly high.     

A Two‐Compartment Fluidized Bed Reactor for CO2 Capture by Chemical‐Looping Combustion

Chemical‐looping combustion (CLC) is a combustion method for a gaseous fuel with inherent separation of the greenhouse gas carbon dioxide. A CLC system consists of two reactors, an air reactor and a fuel reactor, and an oxygen carrier circulating between the two reactors. The oxygen carrier transfers the oxygen from the air to the fuel. The flue gas from the fuel reactor consists of carbon dioxide and water, while the flue gas from the air reactor is nitrogen from the air. A two‐compartment fluidized bed CLC system was designed and tested using a flow model in order to find critical design parameters. Gas velocities and slot design were varied, and the solids circulation rate and gas leakage between the reactors were measured. The solids circulation rate was found to be sufficient. The gas leakage was somewhat high but could be reduced by altering the slot design. Finally, a hot laboratory CLC system is presented with an advanced design for the slot and also with the possibility for inert gas addition into the downcomer for solids flow increase.     

Gas leakage measurements in a cold model of an interconnected fluidized bed for chemical-looping combustion

In chemical-looping combustion (CLC) a gaseous fuel is burnt with inherent separation of the greenhouse gas carbon dioxide. The oxygen is transported from the combustion air to the fuel by means of metal oxide particles acting as oxygen carriers. A CLC system can be designed similar to a circulating fluidized bed, but with the addition of a bubbling fluidized bed on the return side. Thus, the system consists of a riser (fast fluidized bed) acting as the air reactor. This is connected to a cyclone, where the particles and the gas from the air reactor are separated. The particles fall down into a second fluidized bed, the fuel reactor, and are via a fluidized pot-seal transported back into the riser. The gas leaving the air reactor consists of nitrogen and unreacted oxygen, while the reaction products, carbon dioxide and water, come out from the fuel reactor. The water can easily be condensed and removed, and the remaining carbon dioxide can be liquefied for subsequent sequestration.The gas leakage between the reactors must be minimized to prevent the carbon dioxide from being diluted with nitrogen, or to prevent carbon dioxide from leaking to the air reactor decreasing the efficiency of carbon dioxide capture. In this system, the possible gas leakages are: (i) from the fuel reactor to the cyclone and to the pot-seal, (ii) from the cyclone down to the fuel reactor, (iii) from the pot-seal to the fuel reactor. These gas leakages were investigated in a scaled cold model. A typical leakage from the fuel reactor was 2%, i.e. a CO₂ capture efficiency of 98%. No leakage was detected from the cyclone to the fuel reactor. Thus, all product gas from the air reactor leaves the system from the cyclone. A typical leakage from the pot-seal into the fuel reactor was 6%, which corresponds to 0.3% of the total air added to the system, and would give a dilution of the CO₂ produced by approximately 6% air. However, this gas leakage can be avoided by using steam, instead of air, to fluidize the whole, or part of, the pot-seal. The disadvantages of diluting the CO₂ are likely to motivate the use of steam.     

基于Aspen模拟费托合成与CO_2再利用系统

建立了集成费托合成与碳还原反应系统的模型,采用Aspen软件进行仿真分析和计算,重点分析碳气化反应过程及费托合成的产物分布。在煤气化联合循环发电系统中集成该模块,CO2与焦炭发生还原反应得到CO,与来自煤气化单元的H2在费托合成反应器里合成液体燃料,未反应完的合成气用于燃气轮机联合循环发电。针对碳还原反应器和费托合成反应器两部分进行了模拟分析,研究了反应条件对产物的影响。分析结果表明回收CO2制取具有高附加值的液体燃料是CO2再利用的一条有效途径。