Planning the Experiment

The experimental unit, shown on the previous page, is the simplest assembly that can be used for high-pressure kinetic studies and catalyst testing. The experimental method is measurement of the rate of reaction in a CSTR (Continuous Stirred Tank Reactor) by a steady-state method. 

It is assumed that the experiments will be conducted at 70 atm (V.lkPa) pressure or lower. Here the pressure rating of the flow controller limits the maximum pressure for the entire unit. The ROTOBERTY is rated for higher pressure, and upgrading the rest to higher pressure can be done when needed. 

The synthesis gas comes premixed for the desired composition in a high pressure cylinder, e.g., DOT3AA6000 that has 1.5 ft = 42 liter volume. If this cylinder is charged to 380 atm and used down to 80 atm it holds as useful volume (380 - 80) 42 = 12,600 normal liter of synthesis gas. This is 562 g-mol. 

The catalyst is a commercial low-temperature Cu-based shift catalyst that makes methanol at high pressure. Of this, V = 20 cm, equal W = 26.5 g is charged in form of 3/16 (4.76 mm) regular cylinders. 

If using GHSV = 10,000 h , the feed is, F = V GHSV = 20 (104) cm or 200 liters/h. Therefore, the 12.600 normal liters in the cylinder will be enough for 60 hours of operation. During these 60 hours, effects of temperature and conversion (by changing space velocity) can be studied at the one, given gas composition in the cylinder. 

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Many other questions must be considered in planning the experiment ... 

Is the Experiment Properly Planned to Provide Significant Data One cannot directly measure a reaction rate. One is restricted to measurements of the concentrations of various species or of a physical property of the system as a function of time. Thus one must plan the experiments so as to obtain significant differences in the quantities that are observed in the laboratory. In a properly planned experiment the... 

In general an analysis of a system in which noncompetitive parallel reactions are taking place is considerably more difficult than analyses of the type discussed in Chapter 3. In dealing with parallel reactions one must deal with the problems of determining reaction orders and rate constants for each of the individual reactions. The chemical engineer must be careful both in planning the experiment and in analyzing the data so as to obtain values of the kinetic con-... 

Combinatorial chemistry and HT E are powerful tools in the hands of a scient ist, as they are a source for meaningful consistent records of data that would be hard to obtain via conventional methods within a decent timeframe. This blessing of fast data acquisition can turn into a curse if the experimentalist does not take precautions to carefully plan the experiments ahead and the means of handling the data and analyzing them afterwards. The two essential elements that ensure a successful execution of ambitious projects on a rational and efficient basis are, therefore, tools that enable the scientist to carefully plan experiments and get the most out of the minimum number of experiments in combination with the possibility of fast and reliable data retrieval from databases. Therefore, experimental planning and data management are complementary skillsets for the pre- and post experimental stages. 

A number of computer software packages are available to the analyst to assist in the planning and execution of both method development and validation experiments. The attraction of these systems is that they can automate the validation process from planning the experiment to test execution to the presentation of the data in a final report form. 

Ghosh, S., Ed. (1990), Statistical Design and Analysis of Industrial Experiments, Dekker, New York, NY. Gibson, R.J. (1968), Experimental Design, or Happiness is Planning the Experiment, Bioscience, 18,223-225. Gitlow, H., Gitlow, S., Oppenheim, A., and Oppenheim, R. (1989), Tools and Methods for the Improvement of Quality, Irwin, Homewood, IL. 

In order to optimize the information content of experiments, it is wise to plan the experiments ahead in a well defined manner. Formal ways to plan... 

Label all glassware and equipment that will be used with special adhesive tape labeled Radioactive. Plan the experiment so that a minimal number of transfers of radioactive materials is required. This will reduce the amount of contaminated glassware. 

The electrical discharge offers the most convenient and cheapest method for producing chemical reactions by electronic activation. It is difficult, however, to plan the experiments so as to obtain material of theoretical significance because so many different phenomena are simultaneously involved and the measurements of ionization and energy input for chemical action are indirect. 

Let us revert to the case of linear, open or closed sequences with only one overall reaction, and let us assume that the reaction has been followed nearly to completion. It will follow from the sequel that in kinetic experiments it is always advisable to plan the experiments so that the determination of the degree or the number of advancement takes place at equidistant times even when the reaction comes near to completion, where the change is slow. 

It is worth noting that, prior to NR measurements, the potential energy surface for the dissociations of [oxazolidine]+ was mapped by Gaussian 2(MP2) calculations and the energy and kinetic data obtained computationally were used successfully to plan the experiments [157]. 

The two (or possibly three) partners working on a given special project should plan the experiment together, starting 3 or 4 weeks in advance, and should discuss their ideas frequently with an instructor or a teaching assistant. All work done in the laboratory should be supervised by an experienced research worker in order to avoid safety hazards. 

They had planned the experiment on the following basis. The two mechanisms differed as to whether or not a free alkyl radical is an intermediate. The mtvst likely structure for such a radical, they thought, was flat—as, it turns out, it very probably is—and the radical would lose the original chirality. Attachment of chlorine to either face would be equally likely, so that an optically inactive, racemic product would be formed. That is to say, the reaction would take place vitil racemization (see Fig. 7.3). 

Detoxification of the cell culture medium with one of the above-described methods takes 1-2 h. This should be taken into consideration when planning the experiments and care should be taken over storage of the cells whilst treating the medium. 

Always plan the experiment in advance and note any unfamiliar methods or potentially hazardous procedures. If you are supervising staff or students who will carry out the experiment make sure that you explain any unfamiliar procedures clearly and concisely. 

The general functions allocated to the microprocessor [14] are thus (a) enabling the operator to plan the experiments via the keyboard entry (b) controlling the robot s motion (c) effecting communication between robot, peripherals and instruments and (d) data acquisition and processing. 

Perhaps this is what happened when the data were analyzed for this reaction and that is why the kinetics we have used are first order in A and "zero order" in B, that is, independent of B. Maybe this reaction rate only appears to be first order in A at the conditions under which the experiment was run, when in fact it is really first order in A and in B. If this should prove to be the case, then the first-order rate expression for the reaction of A and B to give D and E is actually pseudo-first order, rather than true first order. A pseudo-first-order reaction may really be second order when we analyze the data and plan the experiments more carefully. 

A researcher is motivated to do experiments because of a desire to solve certain practical problems (or so we think). We wrote this book to show how, by appl3dng statistical techniques, the efficiency of finding solutions to experimental problems can be improved. We would hke to teach the reader to take full advantage of statistical techniques, not only for analyzing experimental results, but also — and principally — for systematically planning the experiments prior to making any measurements. 

The compositional Box design [4], for three input variables was used to plan the experiments. This design demanded defining three material variables (which were later transformed into coded values), their ranges and technical properties to be selected as representative. 

Process of planning the experiment so that sufficient data will be collected for the statistical analysis, to... 

Broadening the possibilities on planning the experiments aimed at specifying the chain reaction mechanisms. 

Burla, M., Laniado, E., Romani, F., Tagliavini, P, 2001. The Role of Decision Support Systems (DSS) in Transportation Planning the Experience of the Lombardy Region. Proa of Seventh International Conference on Competitum cuid Ownership in Land Passenger Transport, Molde, Norvay, 25-28 June 2001. 

Plan the experiments. Once the factors have been selected, their ranges have been defined and the model to be applied has been postulated, this step requires only a few minutes. 

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