Hydrogen feed

Table 2.2 gives the compositions of the reactor feed and effluent streams. Calculate the conversion, selectivity, and reactor yield with respect to (a) the toluene feed and (b) the hydrogen feed. 

The hydrogen feed contains methane as an impurity at a mole fraction of... 

Hydrogen lost in purge = 1554U Hydrogen feed to the process = 1554a + 269.2... 

In Du Pont patents (116) the catalyst is prepared by spray-drying a mixture of colloidal siUca or other carriers and Pt/Pd salts. Aqueous hydrogen peroxide solutions up to 20 wt % ate reported for reaction conditions of 10—17°C and 13.7 MPa (140 kg/cm ) with 60—70% of the hydrogen feed selectively forming hydrogen peroxide. 

Distillation of Hquid hydrogen as a method for separating deuterium received early consideration (10,58) because of the excellent fractionation factor that can be attained and the relatively modest power requirements. The cryogenic temperatures, and the requirement that the necessarily large hydrogen feed be extremely pure (traces of air, carbon monoxide, etc, are soHds at Hquid hydrogen temperature) have been deterrents to the use of this process (see... 

A hydrogen stream at 300 K and atmospheric pressure has a dew point of 275 K, It is to be further humidified by adding to it (through a nozzle) saturated stream at 240 kN/nr at the rate of 1 kg steam- 30 kg of hydrogen feed. What will be the temperature and humidity of the resultant stream ... 

Continuous Model "C0NGAS". This model predicts performance of an ideal continuous wellstirred polyreactor. The model system consists of a continuous backmix reactor in which the total powder volume is held constant. There are four inlet streams 1) Makeup of pure propylene, 2) Catalyst feed, 3) Hydrogen feed, and 4) Recycle. The single effluent powder stream is directed through a perfect separator that removes all solids and polymer and then the gases are recycled to the reactor. The makeup propylene is assumed to disperse perfectly in the well-mixed powder. 

Optimization of the catalyst layer composition and thickness in PEFCs for maximum catalyst utilization in operation on air and on impure hydrogen feed streams [Wilson, 1993 Springer et al., 1993]. 

The liquid stream can readily be separated into relatively pure components by distillation, the benzene taken off as product, diphenyl as an unwanted byproduct and the toluene recycled. It is possible to recycle the diphenyl to improve selectivity, but it will be assumed that is not done here. The hydrogen feed contains methane as an impurity at a mole fraction of 0.05. The production rate of benzene required is 265 kmol-lr1. Assume initially that a phase split can separate the reactor effluent into a vapor stream containing only hydrogen and methane, and a liquid containing only benzene, toluene and diphenyl, and that it can be separated to produce essentially pure products. For a conversion in the reactor of 0.75,... 

The deprotection of carbobenzyloxy protected phenylalanine was carried out in a low-pressure test unit (V= 200 ml) equipped with a stirrer, hydrogen inlet and gas outlet. The gas outlet was attached to a Non Dispersive InfraRed (NDIR) detector to measure the carbon dioxide. During the reaction the temperature was kept at 25 °C at a constant agitation speed of 2000 rpm. In a typical reaction run, 10 mmol of Cbz protected phenylalanine and 200 mg of 5%Pd/C catalyst were stirred in a mixture of 70 ml ethanol/water (1 1). The Cbz protected phenylalanine is not water-soluble but is quite soluble in alcoholic solvents conversely, the water-soluble deprotected phenylalanine is not very soluble in alcoholic solvents. Thus, the two solvent mixture was used in order to keep the entire reaction in the solution phase. Twenty p.1 of the corresponding modifier was added to the reaction mixture, and hydrogen feed was started. The hydrogen flow into the reactor was kept constant at 500 ml/minute and the progress of the reaction was monitored by the infrared detection of C02 in the off-gas. 

The T-STAR ebullated bed is shown schematically in Fig. 6. The figure demonstrates that a uniform catalyst distribution is maintained throughout the reaction chamber via the upward flow of the hydrogen, feed oil, and recycle oil. The internal recycle allows for increased conversion and assists in maintaining a uniform temperature throughout the reactor. Careful monitoring of the temperature in an ebullated bed... 

Note that these equations allow the residence time and conversion to be computed, but other process issues are neglected. For example, although assumption 1 is considered, any solvent exhibits some vapor pressure and thus can be extracted by the outlet hydrogen feed. 

The theoretical minimum work for hydrogen liquefaction depends on the pressure of the hydrogen feed, the rate of ortho-para conversion and the temperature difference between ambient temperature and the temperature of the liquid hydrogen. The following formula is valid for ambient input and output pressures ... 

The theoretical minimum demand of work for hydrogen liquefaction depends on the pressure (Fig. 12.3). At a hydrogen feed-gas pressure of 0.1 MPa, the theoretical minimum demand of work of a liquefaction is 3.92kWh/kg of LH2 (Peschka, 1992). 

Fig. 14.17 Relative current density for various anode compositions as a function of increasing CO concentrations added to a pure hydrogen feed to the anode / re = 840 mA cm-2, at 0.5 V, for platinum/carbon.

Sulfur and carbon monoxide can be killers (literally) with hydrogenation catalysts. It will poison them, making them completely ineffective. Some sulfur often shows up in the benzene feed, carbon monoxide in the hydrogen feed. The alternatives to protect the catalyst are either to pretreat the feed and/or the hydrogen or to use a sulfur resistant catalyst metal like tin, titanium, or molybdenum. The economic trade-offs are additional processing facilities and operating costs vs. catalyst expense, activity, and replacement frequency. The downtime consequences of catalyst replacement usually warrarit the more expensive treatment facilities. 

Catalytic reactions were carried out in the isothermal glass batch reactor installed in a shaker and connected to a gasometrical burette. The reactor was equipped with two inlets one for catalyst, solvent, and substrate, and one for hydrogen feeding. The total volume of fluid phase is 32 mL. Hydrogen consumption was controlled by... 

Catalytic hydrogenation in supercritical carbou dioxide has been studied. The effects of temperature, pressure, and CO2 concentration on the rate of reaction are important. Hydrogenation rates of the two double bonds of an unsaturated ketone on a commercial alumina-supported palladium catalyst were measured in a continuous gra-dient-less internal-recycle reactor at different temperatures, pressures, and C02-to-feed ratios. The accurate control of the organic, carbon dioxide, and hydrogen feed flow rates and of the temperature and pressure inside the reactor provided reproducible values of the product stream compositions, which were measured on-line after separation of the gaseous components (Bertucco et al., 1997). 

The methanation reaction is primarily used to remove any traces of CO and C02 in the hydrogen feed gas for ammonia synthesis. The reaction has been known for more than a century [141]. This reaction has found renewed interest in connection with the transformation of coal to natural gas. The hydrogen for ammonia synthesis is here normally produced by steam reforming with subsequent water gas... 

As discussed in a later section, H2S is an inhibitor for the catalytic site responsible for direct sulfur extraction. Thus, if the H2S partial pressure could be lowered in the reactor, the desulfurization rate could be increased. The simplest means to achieve this goal is through increased hydrogen recycle rates or increasing the hydrogen/feed ratio. Such changes are expensive and can in some instances lower the overall thoughput of the feed. 

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