Methane production from synthesis gas using a mixed culture ofR. rubrum M. barkeri,and M. formicicum

The components of synthesis gas, CO, H₂, and CO₂, may be converted into CH₄ biologically through either acetate or H₂/CO₂ as intermediates. Of these two routes, conversion through H₂/CO₂ is preferred. This paper presents results of mixed-culture studies employing the photosynthetic bacteriumR. rubrum for converting CO to CO₂ and H₂ by the water gas shift reaction and two methanogens,M. formicicum andM. barkeri, for converting CO₂ and H₂ into CH₄. Results are presented for triculture operation in two types of reactors, the packed bubble column and the trickle-bed reactor.     

Methane conversion to C2 hydrocarbons in solid electrolyte membrane reactors

Solid electrolyte membrane reactors (SEMRs) have been used to both study and influence catalytic reaction rates. Methane coupling is the reaction most thoroughly and intensively studied in these membrane reactors. In the last 20 years, oxygen ion (O²⁻), proton (H⁺) and mixed (O²⁻-e⁻, H⁺-e⁻) conducting membranes have been tested in order to maximize the conversion of methane to C₂ compounds. The present review contains the fundamental operating principles of the various SEMR types and their applications in this reaction. The difficulties that should be overcome in order to promote this SEMR process to an industrial scale are discussed.     

Flow injection spectrophotometric method for chloride determination in natural waters using Hg(SCN)(2) immobilized in epoxy resin

A flow injection (FI) spectrophotometric method was proposed for the determination of chloride ion in natural waters. The determination of chloride was carried out by reaction with Hg(SCN)₂ immobilized in an epoxy resin bead in a solid-phase reactor (SPR) and the thiocyanate ions released were determined spectrophotometrically at 480 nm after complexing reaction with Fe(III). The analytical curve for chloride was linear in the concentration range from 5.6 × 10⁻⁵ to 2.2 × 10⁻⁴ mol l⁻¹ with a detection limit of 1.4 × 10⁻⁵ mol l⁻¹. The relative standard deviation (R.S.D.) was 2.2% for a solution containing 2.2 × 10⁻⁴ mol l⁻¹ (n = 10). The simple manifold allows a routine analytical frequency of 100 determinations per hour. The main advantage of the developed method is the 400% reduction of the Hg waste solution generated when compared to conventional methods for chloride determination based on the same spectrophotometric reaction.     

催化裂化装置沉降器内结焦的微观结构及其生长过程的分析

对催化裂化装置（FCCU）沉降器内结焦的微观结构进行分析，结果表明，结焦形态主要有4种，丝状焦、滴状焦、块状焦和颗粒状焦。各种结焦形态的成因机理不同，微观结构及生长过程也不同。丝状焦是由铁、镍金属元素催化烃类气体，以及易生焦物发生脱氢缩合反应，以催化剂颗粒形成结焦中心并逐渐长大形成细丝状焦炭；滴状焦是由稠环芳烃脱氢缩合反应而生成，高沸点未汽化油滴黏附在催化剂颗粒或器壁表面形成“焦核”，即由重芳烃、胶质、沥青质脱氢缩合反应和二烯烃聚合环化反应而生成的；块状焦是高沸点未汽化油滴相互溶解后，再脱氢缩合反应或聚合环化反应而形成的结焦；颗粒状焦是油气在气相中脱氢缩合反应或聚合环化反应形成的微小结焦颗粒相互团聚形成的颗粒簇。催化裂化装置沉降器内的结焦一般是上述几种结焦过程的组合，是催化结焦和非催化结焦过程共同作用的结果。     

Modeling of a counterflow plasma reactor

Modeling of a counterflow plasma reactor is presented, using liquid injection for the synthesis of fine particles. An experimental reactor has been developed in this laboratory, and feasibility has been demonstrated for synthesizing advanced ceramic powders. The flow field calculations show two major recirculating regions which are of importance for increasing the particles' residence time inside of the reactor. In addition, the temperature within these recirculation zones remains relatively uniform. For simulation, water droplet trajectories have been calculated for droplets produced by an injection probe. It is shown that the droplets in a size range below 50 m in diameter will follow the streamlines and evaporate completely within a short traveling distance. This finding suggests that this reactor configuration provides a favorable environment for the synthesis of fine particles using liquid precursors.     

Use of kinetic plots for relative assessment of reactor throughput and energy consumption

The progress of high temperature processes is generally described in terms of variation of the degree of conversion () with time (t). The present paper outlines a procedure for making use of-t plots for comparative assessment of productivity and energy requirements for a test system with respect to a reference, on the basis of some simplifying assumptions. It is assumed that the throughput is inversely proportional to reaction time as in the case of batch reactors and plug flow reactors. It is also assumed that the energy requirement is a simple function of process temperature. The principles outlined is illustrated with reference to some laboratory data for reduction of iron oxide by coal.The authors wish to thank Prof. P. R. Rao, Director National Metallurgical Laboratory, Jamshedpur, India, for providing facilities for experimental work and for according permission to publish this work.     

Continuous fermentation for the production of citric acid from glucose

Citric acid is finding new areas of use each year and the demand for the acid is constantly increasing. Being a bulk chemical, the continuous production of citric acid would be advantageous. The paper presents the results from ammonia limited batch and continuous fermentations using the yeast strainSaccharomycopsis (Candida) lipolytica (NRRL Y-7576). Mathematical models were developed for growth and glucose utilization in batch and continuous culture. Cell and acid yields appeared to be almost the same in batch and continuous culture. The specific production rates were found to be constant, equal to 0.053 g/g h, in the batch fermentations but varied in the continuous experiments from 0 to 0.11 g/g h depending on the fermentation conditions. Continuous production in a single stage CSTR was studied for over 1,000 hours without shutdown.     

Adsorption Characteristics of Pb(II) and Cr(III) onto C‐4‐Methoxyphenylcalix[4]Resorcinarene in Batch and Fixed Bed Column Systems

A study on the adsorption characteristics of Pb(II) and Cr(III) cations onto C‐4‐methoxyphenylcalix‐[4]resorcinarene (CMPCR) in batch and fixed bed column systems has been conducted. CMPCR was produced by one step synthesis from resorcinol, 4‐methoxybenzaldehyde, and HCl. The synthesis was carried out at 78 °C for 24 hours and afforded the adsorbent in 85.7% as a 3:2 mixture of C_4ν:C_2ν isomer. Most parameters in batch and fixed bed column systems confirm that CMPCR is a good adsorbent for Pb(II) and Cr(III), though Pb(II) adsorption was more favorable than that of Cr(III). The adsorption kinetic of Pb(II) and Cr(III) adsorptions in batch and fixed bed column systems followed a pseudo 2ⁿ order kinetics model. The rate constant of Pb(II) was higher than that of Cr(III) in the batch system, but this result was contrary to the result obtained in a fixed bed column system. Desorption studies to recover the adsorbed Pb(II) and Cr(III) were performed sequentially with distilled water and HCl, and the results showed that the adsorption was dominated by chemisorption.     

化学模拟在反应堆水化学课程中的应用

高温高压化学反应对反应堆设备的可靠性、反应堆性能的控制、核电站运行的安全持久性等具有重要影响，但相关实验难以在高校教学中开展。借助PHREEQC程序及最新热力学数据，建立了反应堆一回路硼酸-氢氧化锂添加配比、腐蚀沉淀物产生及二回路pH控制方案的化学反应模型。运用化学模拟来教学，促进了学生对所学知识的理解与掌握，丰富了现代教学方法。相关模型对核电企业的培训也具有一定参考价值。     

Continuous segregation of binary heterogeneous solids in a fast-fluidized bed

Continuous segregation of binary heterogeneous solids (different density mixtures) is carried out in a gas–solid fluidized bed to study the effects of gas velocity, solids feed rate, feed composition and density difference of solids on the separation factor (recovery of flotsam at top outlet) and the quality of the product (purity of flotsam at top outlet) in a continuous fast-fluidized bed. The holdup of the bed material is obtained in each experimental run. It is observed that the separation factor decreases with increase in solids feed rate or density difference of solids, and increases with gas velocity or proportion of flotsam in the feed. The quality of the product decreases with increase in gas velocity or solids flow rate, and increases with feed composition or density difference of solids. The experimental results show that the separation factor and the quality of the product are more sensitive to gas velocity than to other operating parameters. Empirical correlations for predicting the separation factor and quality of the product are proposed based on the Richards model for individual flotsam mass fraction in the feed, and the predictions agree satisfactorily with the present experimental data.