Identify precursors Stage

Infrared spectroscopy can be considered as the first important modem spectroscopic technique that has found general acceptance in catalysis. The most common application of infrared spectroscopy in catalysis is to identify adsorbed species and to study the way in which these species are chemisorbed on the surface of the catalyst. In addition, the technique is useful in identifying phases that are present in precursor stages of the catalyst during its preparation. Sometimes the infrared spectra of adsorbed probe molecules such as CO and NO give valuable information on the adsorption sites that are present on a catalyst. 

To draw a comparison between the previous results and the results from applying this protocol, the ten precursors already presented in Table 7 are taken for further analysis. From the derived precursors in the previous stage, which are based on analysing deviations during six months, a prioritized list of precursors is derived. The derived risk matrix for all ten identified precursors is depicted in Figure 32. Note that no lower aggregation level precursors were present amongst the ten identified precursors. 

The modified protocol is described below, starting with identifying precursors from the accident trajectory. When precursors can be identified in the accident trajectory, they become subject of analysis, as stated in Stage 4 of the protocol. The elements on... 

In this part of study, we have investigated the effect of a range of iron manganese oxide catalysts preparation variables at the precursor stage upon the structure of these materials, and the subsequent influence these structural effects have on the activity of the final calcined catalysts. The optimum preparation conditions were identified with respect to the catalytic activity for the conversion of synthesis gas to light olefins. 

With the developed concepts, a number of field experiments were conducted in the chemical process industry. A first experiment was carried out in a small company in The Netherlands. From this first trial, it was evident that the concepts of precursors, the model of the organisational control process and the structure of these concepts had to be adapted to obtain better and more reliable results. The improvements led to the development of a structured protocol of seven clearly defined stages. By applying this 7-stage protocol to the data of the small company, safety risks could pro-actively be identified and the accidents which the company had already experienced, could be explained. 

That precursors are frequently observed in accident trajectories was stated in the previous Section. In this Section 17 recent accidents in the Dutch chemical process industry are taken and their accompanying precursors and ineffective control processes in the companies identified. This study is executed from hindsight using limited accident information which is the reason for adapting the analysis protocol so that the results of most stages can still be retrieved. 

In the previous Chapter it was shown that the developed protocol for analysis identified the ineffective control elements causing the precursors prior to accidents. However, due to the lack of detailed accident information the conclusions were limited. To perform the analysis, using the developed 7-stage protocol pro-actively (before any accident occurs), cases have to be selected on which the analysis can be performed and from which reliable and generic conclusions about safety indicators and the performance of current safety management systems can be obtained. The next sub-Section will discuss the selection criteria to select suitable cases. 

For each individual company, approximately 50 precursors were derived. For reasons of conciseness, only the top 20 precursors from each company are shown in Appendix B. This list of precursors is derived after prioritizing all precursors as discussed in the next Stage, see sub-Section 7.2.3. The top 20 precursors identified in company A, are shown in Table 16. 

From the four case studies several suggestions for improvement were made, according to the identified latent conditions and specific precursors. However, the implementation and validation of these suggestions was not performed and are recognised as steps still missing in the final validation of the 7-stage protocol. The analysis was performed in close co-operation with company employees and the remedies implemented were derived together with the employees. As Schein (Schein, 1999) clearly states, the success of the remedies depends heavily upon the involvement of the company employees, because they know what will work and are ultimately responsible for the implemented remedy and its consequences. 

The IR studies of Idelson and Blout (53) demonstrated that in dioxane the initially-formed polymer possessed a random-coiled structure (described by the authors as the /3-form). As the reaction proceeded a new material appeared, which was identified through its IR spectrum as the a-helix. This stage of the process coincided with the onset of a fast reaction. By using a deuterated n-hexyl amine as the initiator a labelled /S-peptide was prepared. This was used in turn to initiate further polymerisation which yielded an a-peptide. The isolation of the latter and its analysis proved that the a-peptide contained the expected percentage of deuterium, and hence the /S-polymer had to be the precursor of a-peptide. 

---