Hydrogen-to-hydrocarbon ratio

Hydrodearomatization (HDA) was investigated on the mentioned catalysts in temperature range 260-360°C, at total pressures 35-80 bar, hydrogen to hydrocarbon ratios (H2/HC thereafter) 200-1000 Nm3/m3 and liquid hourly space velocity (thereafter LHSV) 0.75-4.0 h"1. The experiments were carried out on catalysts of steady-state activity, in continuous operation. 

Fig. 20 Ratio of substituted C-C cleavage to unsubstituted C-C cleavage of 1,3-DMCH over Ir on different supports. Reaction was conducted at 593 K and 3540 kPa. Hydrogen to hydrocarbon ratio was kept at 30. Without considering secondary hydrogenolysis, the ratio (2-MC7 + 4-MC7)/ 2,4-DMC6 would represent the ratio of (a + b)/c cleavage. The statistical value of (a + b)/c is 2. A = Ir/Al203 O = Ir/Si02 = Ir/Ti02. Adapted from ref. 49.

As a result of the studies discussed above, a reasonably consistent picture of the kinetics and mechanism of the dehydrocyclization reaction over oxide catalysts has evolved. However, as pointed out earlier in this section, relatively few kinetic data have been reported for dehydrocyclization over platinum-alumina reforming-type catalysts. The data which have been reported include those of Hettinger and co-workers (H7), who studied the dehydrocyclization of re-heptane over platinum catalysts. These investigators found that the rate of dehydrocyclization decreased with increasing total pressure at a constant hydrogen-to-hydrocarbon ratio (Fig. 9). They also reported that the extent of dehydrocyclization was substantially greater for re-nonane than for re-heptane, which is consistent with the results obtained on oxide catalysts. In a later study of the kinetics... 

In a series of studies, the variation of the turnover number for the dehydrogenation reaction (the number of product molecules/platinum surface atoms/second) with the hydrogen to hydrocarbon ratio at a constant hydrocarbon pressure of 4 x 10"8 Torr was determined. The results are shown in Fig. 20 for the several stepped surfaces studied. The reaction rates increase with increasing hydrogen to hydrocarbon ratio. If no hydrogen is introduced into the reaction chamber, the catalyst behaves very differently. No benzene... 

The reaction conditions were as follows temperature 482 <>C, pressure 520 kPa, liquid space velocity (WHSV) 2 h l, hydrogen to hydrocarbon ratio 3. 

Carbon laydown increases as the hydrogen-to-hydrocarbon ratio (HHCR) decreases.47 The variation of ageing rate with HHCR is very steep for HHCR < 10 molar (Fig. 6.5).27 Lowering the Weight-Hourly Space Velocity (WHSV) at constant HHCR increases carbon laydown.47... 

Fig. 6.5 Catalyst ageing versus hydrogen-to-hydrocarbon ratio (from Ref. 27).

The catalyst used for the reaction was prepared according to the procedure of Ciapetta and Hunter (f) and consisted of 5 wt. % of nickel deposited on silica-alumina cracking catalyst. The reaction was performed in a flow system under 25 atm. of pressure, at 360°, homly liquid space velocity of 1.0, and the molar-hydrogen-to-hydrocarbon ratio of 4 1. 

It can be seen that yields up to 86-98% could be obtained with slow space velocities and high hydrogen to hydrocarbon ratio. The use of a coprecipitated chromia-alumina catalyst did not improve the hydrogenation, but the presence of carrier (alumina) had a purely diluting effect on active chromia. Experiments at superatmospheric pressure (33 atm.) in a flow system showed that hydrogenation of octene could be achieved to the extent of 82% at much lower temperatures (200°) and higher space velocities (4.0-5.0 hourly liquid space velocities). 

Operating conditions XyMax and AMHAI units operate with a high space velocity and a low hydrogen-to-hydrocarbon ratio, which results... 

Catalytic reforming of straight run naphthas is a very important process for octane improvement and production of aromatic feedstocks for petrochemical industries. Generally, the reforming is carried out in three or four fixed bed reactors which operate adiabatically at temperatures between 450 and 520°C, total pressures between 10 and 35 atm and molar hydrogen-to-hydrocarbon ratios between 3 and 8. 

For CCR reformers, the typical operating variables for a given feedstock are reactor temperature, feed rate (or space velocity), reactor pressure, hydrogen to hydrocarbon ratio (H2/HC) and the activity of the catalyst By making changes in the process variables, refiners can make significant shifts in the product distribution. 

Additionally, we must also enter the Hydrogen-to-Hydrocarbon ratio for the recycle process in the Reformer model. The typical range of this value for CCR reforming units is 3-4. Reforming plants routinely measure this value and we expect to enter accurate values. The product separator refers to the conditions of the first separator after leaving the last reforming reactor. This value should be accurate if we do not plan to build a downstream fractionation model. 

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