Industrial catalysts quality control

Performance variations of different lots of the same brand of catalyst still are causes of significant plant problems in the industry. Such experiences justify efforts to develop effective quality control procedures for purchased catalysts. Obtaining a clear understanding of required catalyst properties is a first step. Plant problems and unusual events need to be recorded. The history of catalyst performance in the plant is most valuable to have in developing catalyst specifications. 

Quality control of production has, for many years, been a major concern of catalyst manufacturers. Some methods, such as texture analysis of solids and elemental analysis, have been established for a long time. Others, such as X-ray absorption spectroscopy, are more recent. Analysis techniques as a whole, however, have been subject to methodological research enabling the scope and level of interpretation of results to be developed. Recent decades have in particular seen numerous analysis techniques based on the use of radiation and particle beams applied to industrial catalysts. In view of the increasing number of possibilities for analysing this type of solid in detail, we considered it useful to give an up-to-date assessment of the type of information that each technique can offer. 

The analysis of organic matrices dissolved in solvents using ICP-OES is finding an increased number of analytical applications in laboratories worldwide. These methods are important in terms of rapid sample preparation, reduction in contamination, loss of elements through sample preparation, etc. A considerable number of organic-based metal solutions are used in industrial, medical and pharmaceutical applications as initiators, activators, colorants, chemical catalysts, pharmaceutical preparations, etc. and need to be quantified as part of contamination monitoring or quality control. 

Information on specific production methods can be found in the literature [Pinna 1998]. Impregnated catalysts are mainly produced batchwise with discontinuous process steps. Therefore, continuous quality control of the individual catalyst batches is vital (e.g., testing of mechanical strength, performance tests in screening reactors). The process developer must pay special attention to transferring the laboratory recipe to industrial catalyst production. Test production should be carried out relatively early... 

Anyway, an extremely important aspect, common to all the above techniques, is the sample preparation to the analysis. Very often, the pre-treatment procedures are not sufficiently described in scientific publications, making sometimes impossible to reproduce experimental data. It is also important to underline that the analytical reproducibility should be always verified. Analytical reproducibility is influenced not only by the experimental parameters but mainly by the pre-treatment procedures. For this reason, fully automatic equipment performing the catalyst preparation before the analysis is highly recommended, especially when these type of measurements are performed in industrial quality control laboratories. 

Py-LVEIMS and PyHRMS were used in the determination of structure and composition of clinically important polyurethanes, PEUUs (Biomer, Lycra Spandex, Tecoflex and Pellethane) [746]. The antioxidants found in Biomer and Lycra Spandex were identified as well as an AO in Pellethane and an antistatic agent or residual catalyst in Biomer and Lycra Spandex. These tools are valuable for QC of implant material. PyMS is widely used in quality control of industrial products, such as foils and packaging materials [747], silicone and nitrile rubbers [748], can coatings and rubber sealing and tobacco [749]. In particular, it appears that Py-FIMS finds application not only for research in structure determination of non-volatile polymers, but also in product control. Schulten et al. [692] have described the application of Py-FIMS to paints (commercial can coatings), epoxy and polyester resins. Polyamides, acrylic and methacrylic resins, have been analysed in the same way [750-753], Py-FIMS is well suited for these investigations and allows identification of different polymer sub-units, such as monomers, dimers, backbone fragments, etc. Moreover, the technique enables differentiation of the examined compounds, which is of interest to industrial quality control. 

The gradual evolution of more reliable supported metal catalysts required reproducible supports. Industrial processes for the production of pure alumina and sihca were soon developed. This led naturally to the control and measurement of chemical and physical properties at all stages of catalyst production to ensure optimum surface area and pore stractrrre. Controls were at first empirical, and quality depended on consistent production conditions. It was not imtil 1938 that techniques for measttring stuface area and pore volume were introduced and modem methods of catalyst qrrality control and characterization began to evolve. ... 

There are many examples of laboratory catalysts very successful as to activity and selectivity, but unsuitable to industrial development due to lack of mechanical strength, whose measurement is a key part of every quality control for any industrial catalyst. In practice, no catalyst should be loaded in an industrial reactor without having tested its mechanical properties. 

Mechanical strength is a property of utmost importance for the industrial use of heterogeneous catalysts. Abrasion resistance and radial crash strength (for pellets) and attrition resistance (for powders) should be routinely measured for quality control of industrial catalysts before reactor loading or better before catalyst purchasing. Such measurements can be conveniently performed using the respective ASTM standard methods, whose possible improvements are suggested. 

The use of catalysts for exploiting renewable energy sources, producing clean fuels in refineries, and minimizing the by-product formation in industry also fall within the definition of environmental catalysis. In the future, the continuous effort to control transport emissions, improve indoor ah quality, and decontaminate polluted water and soil will further boost catalytic technology. All in all, catalysts will continue to be a valuable asset in the effort to protect human health, the natural environment, and the existence of life on Earth. 

Reproducibility characterizes the preparation of a catalyst as much as the catalyst itself it is of concern to industrial users who want to be assured of the quality of successive charges of catalyst and it also preoccupies the various engineers responsible for developing the catalyst from the laboratory on to industrial manufacture. Indeed, the preparation of a catalyst generally takes place in several rather complex stages dependent on a large number of variables difficult to control simultaneously. The result is that it is indispensable to rapidly verify that the reproducibility of the preparation is feasible, as well as to keep in mind that the formula developed in the laboratory should be capable of extrapolation to pilot scale and to industrial scale under acceptable economic conditions. 

Nevertheless heterogeneous catalysis are convenient to use commercially. Easily prepared solid catalyst pellets, packed in tubes through which reactants flow, satisfy process requirements for simple construction and dependable operation. Control is good, product quality high. It is not surprising that the vast majority of industrial catalytic processes adopt this approach. 

Product quality and efficacy improvements are likely to be driven more from the litigation based developed nations, than by eastern competition, at least in the short-term. In the fine chemical industry the need to produce and isolate only the precise isomer of the active molecule is likely to increase i.e. we need to make the exact molecule we want. Whilst new chemistry, new catalysts and new extractive routes will all play their part so also will the need to precisely define and control the reactions and extractions at a level not currently available and in many instances not yet dreamed of. In the polymer industries, in common with other performance or property products, the ability to produce the specific product for the specific purpose will provide the more lucrative markets. 

The Control of Industrial Pollution Water Quality and Health Aspects of the Chemistry and Analysis of Substances of Concern in the Water Cycle The Role of Wastewater Treatment Processes in the Removal of Toxic Pollutants Sewage and Sewage Sludge Treatment The Chemistry of Metal Pollutants in Water Effects of Pollutants on the Aquatic Environment Important Air Pollutants and Their Chemical Analysis Pollutant Pathways and Modelling of Air Pollution Legislation and the Control of Air Pollution Catalyst Systems for Emission Control from Motor Vehicles Evaluating Pollution Effects on Plant Productivity A Cautionary Tale Epidemics of Non-infectious Disease Systems Methods in the Evaluation of Environmental Pollution Problems Organometallic Compounds in the Environment. 

---