Hydrogen consumption

Table 5.28 gives the modifications in physical/chemical characteristics resulting from deeper and deeper hydrotreatment (Martin et al., 1992). The sulfur contents could thus be reduced to first as low as a few hundred ppm, then to a few ppm. The level of aromatics in the selected example drops from 39% to 7% while the cetane number increases from 49 to 60. Note here that such a treatment, possible through experimental means, does not correspond to current industrial practice because of its high cost and its very high hydrogen consumption. 

By-products of these processes of hydrotreating are gases, H2S, and some naphtha. The hydrogen consumption is relatively high as a function of the required performance. 

Improving the cetane number as well as lowering the aromatics content requires higher partial pressures as well as higher hydrogen consumption. 

Relationship between the residual aromatics content, the hydrogen partial pressure, and the chemical hydrogen consumption (for a SR gas oil). 

For gas oil from catalytic cracking (LCO), reducing the aromatics content to 20 wt. % results in a chemical hydrogen consumption of 3.4 wt % and a cetane number of 40. 

Initial operation at the Wilsonville pilot plant was ia SRC-I mode and later evolved iato a two-stage process (129) by operation ia NTSL mode. NTSL limitations described previously combiaed with high hydrogen consumptions resulted ia subsequent focus on a staged iategrated approach, which was to be the basis for all further studies at Wilsonville. 

Early stmctural determination lends iasight iato the chemical reactivity of vitamin K. Catalytic hydrogenation of vitamin consumes four moles of hydrogen and affords a colorless compound. Because complete hydrogenation of a 1,4-naphthoquiaone stmcture consumes three molecules of hydrogen, consumption of the fourth mole iadicates unsaturation ia the side chain. Reductive acetylation of vitamin affords the diacetate of... 

Lyondell and Sun Oil Co. are the main producers of benzene by disproportionation. Eiaa Oil Co. of Texas has developed the Eiaa T2BX process for toluene disproportionation usiag a proprietary catalyst. The new catalyst is claimed to reduce hydrogen consumption and is suitable for feeds containing small amounts of moisture (53). A commercial production unit was started up ia the fall of 1985. 

Hydroxylamine sulfate is produced by direct hydrogen reduction of nitric oxide over platinum catalyst in the presence of sulfuric acid. Only 0.9 kg ammonium sulfate is produced per kilogram of caprolactam, but at the expense of hydrogen consumption (11). A concentrated nitric oxide stream is obtained by catalytic oxidation of ammonia with oxygen. Steam is used as a diluent in order to avoid operating within the explosive limits for the system. The oxidation is followed by condensation of the steam. The net reaction is... 

Hydrofining usually involves only minor molecular changes of the feed with hydrogen consumption in the range of about 100 to 1,000 cu.ft./bbl. Typical applications include desulfurization of a wide range of feeds (naphtha, light and heavy distillates, and certain residua) and occasional pretreatment of cat cracker feeds. 

Hydrotreating essentially involves no reduction in molecular size with hydrogen consumption less than about 100 cu. ft./bbl. Primary application is to remove small amounts of impurities with typical uses including naphtha and kerosene hydrosweetening. 

Consuming hydrogen is mainly a function of the number of benzene substituents. Dealkylation of polysubstituted benzene increases hydrogen consumption and gas production (methane). For example, dealkylating one mole xylene mixture produces two methane moles and one mole of benzene it consumes two moles of hydrogen. 

H2TPR results (Flow rate of 5% H2 = 20cc/min, Ramp rate= lOtl/min) show that Sb modifies the catalyst surface reducibility. The hydrogen consumption on WO3 takes place above 500 °C. It is evident from TPR results that new surface species were formed by Sb addition. The population of such species, that is represented as the area under the new peak, increases with increasing Sb content with the maximum at Sb=0.4 and then decreases with further increasing Sb content. 

Maximum temperatures and hydrogen consumption during the temperature programmed reduction of Cu/oxides by hydrogen, and NO taken up by Cu atom. 

TPR experiments were performed at different amounts of sulfur on a Cu/Zr02 (Fig. 2). SO2 addition induces a modification of the TPR profile the reduction peaks are shifted toward higher temperatures. The total hydrogen consumption is decreased by 50% for the Qrst SO2 dose, then remains constant. 

The reaction rate was calculated from hydrogen consumption, from pressure drop. As the hydrogen consumption rate was dependent on amount and purity of substrate, catalyst weight and metal content, conversion rate was given (%/min mg Pd), the measured total hydrogen consumption was taken equivalent with 100% conversion. 

The substrate, catalyst and solvent were placed into a glass liner equipped with a magnetic stir bar. The liner was placed in a 250 mL steel autoclave that was then charged at r.t. first with N2, then with H2. The reaction mixture was stirred at r.t. until the hydrogen consumption ceased, after which the H2 was vented, the autoclave flushed with N2 and the reaction mixture filtered off on glass filter. The solution was evaporated and the products crystallized and filtered. The crystalline mixture contained the hydrochloride salt of diamino resorcinol and aniline In order to separate completely diamino resorcinol and aniline, the product mixture has to be recrystallized from hydrochloric acid solution. 

Finally the hydrogenation in methanol and a subsequent acidification under hydrogen atmosphere turned out to be most successful (Figure 14.3.). After ceasing of the hydrogen consumption, hydrochloric acid solution was added to the reaction... 

Figure 2. Representative Hydrogen Consumption Plot. (Reproduced with permission from Ref. 9. Copyright 19d7 Pergamon Journals Ltd.)...

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