Batch process monitoring using on-line MIR spectroscopy

Many high quality products are produced in a batch wise manner. One of the characteristics of a batch process is the recipe driven nature. By repeating the recipe in an identical manner a desired end-product is obtained. However, in spite of repeating the recipe in an identical manner, process differences occur. These differences can be caused by a change of feed stock supplier or impurities in the process. Because of this, differences might occur in the end-product quality or unsafe process situations arise. Therefore, the need to monitor an industrial batch process exists. An industrial process is usually monitored by process measurements such as pressures and temperatures. Nowadays, due to technical developments, spectroscopy is more and more used for process monitoring. Spectroscopic measurements have the advantage of giving a direct chemical insight in the process. Multivariate statistical process control (MSPC) is a statistical way of monitoring the behaviour of a process. Combining spectroscopic measurements with MSPC will notice process perturbations or process deviations from normal operating conditions in a very simple manner. In the following an application is given of batch process monitoring. It is shown how a calibration model is developed and used with the principles of MSPC. Statistical control charts are developed and used to detect batches with a process upset.     

Cationic membranes for phenols production

Ionic Substitution by Electrodialysis is a good alternative to the industrial conversion of sodium salts of phenols into undissociated phenols, conventionally performed through acidification by strong acids. The acidification through electromembranes combines the possibility to achieve high conversion values with the advantage of keeping the process stream separated from the acid stream. The process is performed through cationic membranes; conversion can be obtained also in the absence of electric current, even if slightly better performances can be achieved by applying an electric field. Process feasibility as well as membrane resistance is tested, for the case of model solutions reproducing the main features of the real process streams. Maximum conversion and process rate are greatly affected by the ratio between protons in the acid solution and sodium ions in the process solution. Phenol losses into the acid stream and chloride contamination of the process stream can be reduced by working with diluted process and acid streams.     

Material- und Signalfluß

An industrial production process is considered to be divided into a working process and an information process. Starting point for the information process is the sampling of a material flow. The meaning of “representative” samples as well as questions of continuous and non-continuous sampling methods are discussed. The signals coming out of analysis are arranged in a special way according to statistical methods. Thereafter the information content is calculated by using rules of the information theory. The transmission of the information content within a certain time results in an information flux. The information flux actually required by the working process is compared to the information flux provided by analysis; and both are put into an equilibrium followed by considerations on “necessary and sufficient” analytical actions. It is the aim of analytical information processes to reduce the entropy of the working process to a minimum.     

Monitoring of an industrial process by multivariate control charts based on principal component analysis

The control and monitoring of an industrial process is performed in this paper by the multivariate control charts. The process analysed consists of the bottling of the entire production of 1999 of the sparkling wine "Asti Spumante". This process is characterised by a great number of variables that can be treated with multivariate techniques. The monitoring of the process performed with classical Shewhart charts is very dangerous because they do not take into account the presence of functional relationships between the variables. The industrial process was firstly analysed by multivariate control charts based on Principal Component Analysis. This approach allowed the identification of problems in the process and of their causes. Successively, the SMART Charts (Simultaneous Scores Monitoring And Residual Tracking) were built in order to study the process in its whole. In spite of the successful identification of the presence of problems in the monitored process, the Smart chart did not allow an easy identification of the special causes of variation which casued the problems themselves.     

N，N－二甲基甘氨酸乙酯分解反应机理的理论研究

利用量子化学计算方法MP2／6－31＋G^*研究了N，N－二甲基甘氨酸乙酯在气 相中热分解反应机理，并计算了反应的协同性，得出此反应是一个多步反应过程。 主要有两个阶段：第一个阶级是N，N－二甲基甘氨酸乙酯热分解产生N，－N二甲基 甘氨酸中间体和乙烯，第二个阶段是N，N－二甲基甘氨酸进一步分解生成三甲氨和 二氧化碳。第一个反应阶段为速率控制步骤。研究表明，该反应机理是一个非协同 的质子转移过程。计算结果与实验值吻合。     

Dynamics of glass-forming liquids. XII. Dielectric study of primary and secondary relaxations in ethylcyclohexane

The dynamics of ethylcyclohexane are investigated by high resolution dielectric spectroscopy aiming to characterize the relevant relaxational features of this simple system in its fluid, supercooled liquid, and glassy states. The dielectric signature of structural relaxation is a primary loss peak with amplitude Deltaepsilon=0.01, and a secondary loss process is found in the glassy state. This beta relaxation is compared with a "slow" process revealed by ultrasonics and with previously found gamma and chi processes in similar materials containing the cyclohexyl group. The results suggest that this secondary process is an intramolecular mode rather than a Johari-Goldstein process, consistent with its persistence in the liquid state at slow relaxation times which exceed those of the alpha process. The dielectric activity of such a slow process requires that the dipole magnitude changes with the intramolecular transition, whereas a change in dipole direction only would be masked by the faster structural relaxation.     

The ultra-fast process of picosecond time-resolved energy transfer in liquid cyclohexane by picosecond single-pulse radiolysis

Two formation processes of singlet states of solute molecules in irradiated liquid cyclohexane have been observed by using a single picosecond electron pulse-radiolysis technique. The slower process corresponds to the very fast formation process reported by Beck et al. The faster process is an ultra-fast process which finishes immediately after a picosecond electron pulse, and is hardly quenched by CCl₄ on triethylamine. The ratio of the faster component to the slower component in liquid cyclohexane is very different from that in liquid toluene.     

100% electrostatic application of metallic basecoats

Paint Application by electrostatic high rotation atomizers is the most efficient way of applying spray paint to car bodies in automotive OEM paint shops. Only the 2^nd coat of metallic base coats usually is applied by pneumatic atomizers. The reason for this is due to color/design and process stability questions, both resulting from differences in atomisation and droplet deposition mechanisms of the two paint atomizing processes. The results in an applied metallic film are explained. A path towards a process is outlined, considering not only the spray process itself, but the whole process chain incl. : - design - the repair processes - the manufacturers of plastic parts for the body - the paint manufacturers in terms of paint reformulation and test equipment The success of this process depends on the careful evaluation of the paint shop targets and the consideration of the total process chain.     

偏高岭土水热合成NaY分子筛的机理研究

采用茂名高岭土水热合成NaY分子筛,用IR,XRD,NMR,SEM,HRTEM等分析了其晶化过程。结果表明：偏高岭土水热合成Y型分子筛是固相转变机理,晶化过程是一个扩散-成胶-原位重排的过程。     

Analysis of Volatile Components of Jasmine and Jasmine Tea during Scenting Process

Jasmine tea is widely loved by the public because of its unique and pleasant aroma and taste. The new scenting process is different from the traditional scenting process, because the new scenting process has a thin pile height to reduce the high temperature and prolong the scenting time. We qualified and quantified volatiles in jasmine and jasmine tea during the scenting process by gas chromatography-mass spectrometry (GC-MS) with a headspace solid-phase microextraction (HS-SPME). There were 71 and 78 effective volatiles in jasmine and jasmine tea, respectively, including 24 terpenes, 9 alcohols, 24 esters, 6 hydrocarbons, 1 ketone, 3 aldehydes, 2 nitrogen compounds, and 2 oxygen-containing compounds in jasmine; 29 terpenes, 6 alcohols, 28 esters, 8 nitrogen compounds, 1 aldehyde, and 6 other compounds in jasmine tea. The amounts of terpenes, esters, alcohols, nitrogen compounds, and hydrocarbons in jasmine and tea rose and then fell. The amount of oxygenated compounds of tea in the new scenting process first rose and then fell, while it showed a continuous upward trend during the traditional process. The amount of volatiles in jasmine and tea produced by the new scenting process were higher than that of the traditional scenting process at the same time. This study indicated that jasmine tea produced by the new scenting process had better volatile quality, which can provide proof for the new scenting process.     

聚丙烯腈纤维的预氧化过程的研究

本文通过差热分析、热机械行为、红外光谱、自由基浓度和模量的变化等实验,对采用均聚和共聚的两种聚丙烯腈原丝在氧化过程中出现的现象进行分析,可以看出均聚纤维的自由基反应引发环化较为明显,但由于存在水解反应,因此也存在离子型反应引发环化,而共聚纤维似以离子型引发为主。     

The surface chemistry of Bayer process solids: a review

The Bayer process is used for refining bauxite to smelting grade alumina (Al₂O₃), the precursor to aluminium. The process was developed and patented by Karl Josef Bayer 110 years ago, and has become the cornerstone of the aluminium production industry worldwide. Production of alumina reached 46.8 megatonnes (Mt) worldwide by the end of 1997, with Australia the worlds largest producer of bauxite and refiner of alumina with just under 30% of world production. Although the refining process is well established and the basic theories underpinning it are well defined, the fundamental chemistry of the Bayer process is not well understood. Of particular interest to industrial and academic researchers alike, is the chemistry of the Bayer process solids—aluminium trihydroxide, ‘red mud’ and sodium oxalate. The surface chemistry of these solids is of great industrial importance as the refining industry experiences significant restrictions due to limitations imposed on the process by surface chemical reactions. Of scientific interest is the conceptual advancement of our knowledge and understanding of the nature of surfaces under extreme (non-ideal) conditions. A review of the current literature relating to these important Bayer process solids is thus presented. While not exhaustive, the review is thorough and aims to familiarise the reader with current levels of understanding regarding the nature of Bayer process solids surfaces under Bayer process conditions, and the significant roles these solids play in the overall efficiency of the refining process. It is hoped that this review will provide a useful starting point for researchers new to the area of Bayer process research, whilst also stimulating further fundamental research in this economically and scientifically significant area.     

Effects of multiple-stage membrane process designs on the achievable performance of automatic control

There is limited information from literature on the dynamic operability of membrane processes with multiple stages or loops. Such information is useful for assessing the performance achievable by an automatic controller proposed for a process design before the actual controller is implemented. Based on dynamic modeling of an industrial whey ultrafiltration process with an increasing number of stages up to a maximum of 12, the dynamic responses of the flowrate and concentration of the retentate were obtained. Features of the dynamic responses were used to determine the performance, in terms of quality and speed, that can be achieved by automatic controllers. In particular, limitations on the performance are indicated by features of dynamic responses such as effective time delay and inverse responses. Changes in effective time delay and inverse responses with the number of stages in the whey ultrafiltration process demonstrate a trade-off between process performance and control performance. This trade-off should be considered during process and controller design to maximize the economic return from the production of whey protein concentrates.     

Micronization of tolbutamide using rapid expansion of supercritical solution with solid co-solvent (RESS-SC) process

Micronization of a sulfonylurea antidiabetic agent, tolbutamide, using rapid expansion of supercritical solution with solid co-solvent (RESS-SC) process was investigated in this study. Menthol was selected as the solid co-solvent in the RESS-SC process owing to its high vapor pressure and ease of removal by sublimation. The tolbutamide particles were micronized successfully from its original mean size of 89.4 ??m to the smallest mean size of 2.1 ??m through the RESS-SC process. The use of solid co-solvent in this process enhanced the saturated solubility of tolbutamide in supercritical carbon dioxide and inhibited the particle growth during pressure expansion after the nozzle. In addition, polymorph conversion from form I to form II after the RESS-SC process was confirmed by XRD and DSC analyses. Measurements of the dissolution rate profiles before and after the RESS-SC process were also investigated. It is shown that the micronized tolbutamide by the RESS-SC process had novelty in dissolution behavior compared to that of the original compound. Its dissolution rate was enhanced by 8.8 times after the RESS-SC process.     

Development of Highly Selective Process for Mono-Ethylene Glycol Production from Ethylene Oxide via Ethylene Carbonate Using Phosphonium Salt Catalyst

A new process for the production of mono-ethylene glycol (MEG; HOCH₂CH₂OH) was developed by Mitsubishi Chemical Corporation (MCC) to meet its growing demand in the world. While the MEG selectivity of conventional non-catalyzed process is around 89% under typical conditions, that of the new process exceeds 99%. The key of the high selectivity is the two-step synthesis via ethylene carbonate. The first step reaction is catalyzed by phosphonium salts and generates ethylene carbonate as an intermediate. This is followed by hydrolysis of ethylene carbonate in the second step. Several commercial plants of the new process have already been operated world-wide.     

新型Ni－La催化剂催化甲醇气相羰基化反应

 制备和测试一种全新的甲醇气相羰基化催化剂。催化剂的活性金属为Ni, La为第二组分，本身无催化羰基化活性，采用一种我们自行开发的新型碳分子筛为载体。在制备过程中，采用了一种全新的负载路线，即：以Ni-La双核配合物为金属微晶的前体，使得Ni-La按确定的原子比混合，由此得到全新Ni-La羰基化催化剂。La有很强的助催化作用，与未添加La的Ni催化剂相比，Ni-La催化剂表现出更高的催化活性和选择性。     

Factors that affect the biosynthesis of xylitol by xylose-fermenting yeasts

Xylitol is a sweetener with important technological properties like anticariogenicity, low caloric value, and negative dissolution heat. Because it can be used successfully in food formulations and pharmaceutical industries, its production is in great demand. Xylitol can be obtained by microbiological process, since many yeasts and filamentous fungi synthesize the xylose reductase enzyme, which catalyses the xylose reduction into xylitol as the first step in the xylose metabolism. The xylitol production by biotechnological means has several economic advantages in comparison with the conventional process based on the chemical reduction of xylose. The efficiency and the productivity of this fermentation chiefly depends upon the microorganism and the process conditions employed. In this mini-review, the most significant upstream parameters on xylitol production by biotechnological process are described.     

玻碳电极上多巴胺的氧化还原机理

用电化学方法和光谱电化学方法详细研究了多巴胺(DA)在玻碳(GC)电极表面的反应机理.结果表明DA的电氧化是一个单电子转移过程而不是一个双电子转移过程,在此过程中有半醌自由基中间体存在.用多种电化学手段测定了电极反应动力学参数,提出了新的电极反应机理.