Space weight hourly

WHSV (weight hourly space velocity) = (lb feed/h)/(lb catalyst). 

ALLreviations reactors Latch (B), continuous stirred tank (CST), fixed Led of catalyst (FB), fluidized Led of catalyst (FL), furnace (Furn.), multituLular (MT), semicontinuous stirred tank (SCST), tower (TO), tuLular (TU). Phases liquid (L), gas (G), Loth (LG). Space velocities (hourly) gas (GHSV), liquid (LHSV), weight ( VHSV). Not available, NA. To convert atm to kPa, multiply Ly 101.3. 

Catalyst system Temperature (K) Conditions Pressure (10s Nm-2) Weight hourly space velocity (hr-1) Conversion" (%) Selectivity6 (%) Ethene/butene molar ratio" Reference... 

For the n-Cq reforming and n-C[2 isomerization reactions the catalysts were run in a fixed bed micro reactor equipped with on-line GC analysis. The catalyst, together with a quartz powder diluent, was added to a 6 inch reactor bed. A thermocouple was inserted into the center of the bed. The catalysts were calcined at 350-500°C immediately prior to use and reduced in H2 at 350-500°C for 1 hour. n-Heptane or dodecane (Fluka, puriss grade) were introduced via a liquid feed pump. The mns were made at 100-175 psi with a H2/n-heptane (or n-Ci2) feed ratio of 7 and a weight hourly space velocity of 6-11. 

Benzene hydrogenation was used to probe metal site activity. A 12/1 H2/benzene feed was passed over the catalysts at 700 kPa with a weight hourly space velocity of 25. The temperature was set to 100°C and the conversion of benzene to cyclohexane was measured after 2 hours at temperature. The temperature was then increased at 10°C increments and after two hours, the conversion remeasured. 

Selected conditions and results are shown in Table 2 that are representative of the catalyst performance. Continuous testing of the Ni/Re catalyst compared favorably with the baseline data generated for this catalyst in the batch reactor screening. At 200°C, the overall activity of the catalyst appeared slightly higher in the continuous reactor, achieving 94% conversion at a weight hourly space velocity of 2.5hr 1 (g xylitol/g catalyst/h) and 200°C compared to 88% conversion at an equivalent exposure in the batch reactor of 2.1 hr"1 (g xylitol/g catalyst/h) achieved at the 4 hour sample at 200°C. 

The transformation of n-Ci6, (Aldrich, > 99.9 % purity) was carried out in a fixed bed stainless steel reactor under the following conditions temperature = 220°C, total pressure = 30 bar, H2/n-alkane molar ratio = 20, WHSV (weight hourly space velocity) = 2-100 h 1. WHSV was changed by modifying the catalyst weight and/or the flow rates in order to obtain different conversion values. Before use, the catalysts were reduced in-situ under hydrogen flow at 450°C during 6h. 

Hydroisomerization of n-octane was performed in a flow reactor, in the range of 473-533 K under pressure 1-20 bar, weight hourly space velocity of n-octane was 2,5 g/(g h) and the molar ratio of n-octane H2 =1 5. 

WHSV weight-hourly space velocity (kgolefin/(kgcatalyst h))... 

VHSV = volumetric hourly space velocity WHSV = weight hourly space velocity... 

Figure 17. Time on stream dependence of (a) aniline conversion and (b) NMA yield on Cul-xZnXFe204 at 3000C and WHSV = 3.58 h-1 with a CH30H PhNH2 H20 feed composition of 3 1 1 of (c) Time on stream and weight hour space velocity (inset) dependence of aniline conversion and NMA selectivity on Cu0.5Zn0.5Fe204 at 300°C and WHSV = 3.58 h-1. Note the formation of secondary products at low WHSV.

Catalytic evaluation of the different pillared clays was performed using a microactivity test (MAT) and conditions described in detail elsewhere (5). The weight hourly space velocity (WHSV) was 14-15 the reactor temperature was 510 C. A catalyst-to-oil ratio of 3.5-3.8 was used. The chargestock s slurry oil (S.O., b.p. >354 C), light cycle oil (LCGO, 232 C < b.p. <354 C) and gasoline content were 62.7 vol%, 33.1 vol% and 4.2 vol% respectively. Conversions were on a vol% fresh feed (FF) basis and were defined as [VfVp/V ] x 100, where is the volume of feed... 

Space Velocity The volume or weight of a gas or liquid which flows through a catalyst bed or reaction zone per unit time divided by the volume or weight of catalyst. The terms liquid hourly space velocity (LHS V), and weight hourly space velocity (WHS V), are used to describe this type of flow measurement. High values correspond to short reaction times. 

WHSV (weight hourly space velocity) = (lb of feed/hr)/(lb of catalyst). Other combinations of units of the flow rate and reactor size often are used in practice, for instance. 

Space velocities (hourly) gas (GHSV), liquid (LHSV), weight (WHSV). 

The effect of pressure on the isomerization of n-heptane and n-octane was determined over the Pt//l-zeolite, Mo2C-oxygen-modified and M0O3-carbon-modified catalysts. The weight hour space velocity (WHSV) was changed with the pressure to keep the conversion at a similar level, enabling the effect on the isomerization selectivity and the product distributions to be seen. Other conditions were kept constant. 

Figures 7 and 8 show the comparison of the two catalysts on a weight hourly space time (WHST) basis. The reactor operating conditions were 371C (700F) and 1500 psig. The studies of Sooter (2) and Satchell (3) were, however, conducted at 1000 psig. But this difference is not significant as far as comparison of the two catalysts is concerned, because the two studies revealed that pressure beyond 1000 psig had marginal effect on the activities of Nalcomo 474 catalyst with the Raw Anthracene Oil as the feedstock. Same was the case when Monolith catalyst was used.

Since the surface areas of the two catalysts differed widely, a comparison of activities of the two catalysts on unit surface area basis was made. Figures 9 and 10 represent such a comparison. The abscissa of these graphs is S/Q, where S is the total surface area of the catalyst in the reactor and Q is the volumetric flow rate of oil. S/Q or S/W are quite akin to volume hourly or weight hourly space times. Figure 9 shows that as far as the desulfurization of lighter stock such as Raw Anthracene Oil is concerned, the unit surface activity of the two catalysts is almost the same. But the surface activity towards denitro-genation is higher for the Monolith catalyst than for the Nalcomo 474 catalyst. 

Figure 7. HDS and HDN responses to the change in the weight hourly space time, raw anthracene oil, 1500 psig, 371° C (700° F) (O) Monolith catalyst, (A) Nal-...

A fixed bed reactor described by ASTM Method No. D3907 was employed for catalytic testing. A sour, imported heavy gas oil with properties described in Table II was used as the feedstock. Experiments were carried out at a reactor temperature of 800°K and catalyst residence time (9) of 30 seconds. Liquid and gaseous products were analyzed with gas chromatographs. Carbonaceous deposit on the catalyst was analyzed by Carbon Determinator WR-12 (Leco Corp., St. Joseph, MI). The Weight Hourly Space Velocity (WHSV) was varied at constant catalyst contact time to generate selectivity data of various products as a function of conversion. For certain experiments, conversion was also varied by varying the catalyst pretreatment conditions. 

Figure 7. Activity and selectivity of hydrothermally pretreated (1090°K) catalysts. Conversion was varied by varying weight hourly space velocity.

The large difference in gallery heights for Cr3 53 and Cr1 88-montmorillonites leads to dramatic differences in catalytic reactivity (17). Figure 4 illustrates the conversion of cyclohexane to benzene over both materials at 550°C as a function of reaction time. Both catalysts were pre-reduced under H2 in a continuous flow reactor at 500°C, followed by reaction with cyclohexane (weight hourly space velocity = 3, contact time = 6 sec, He carrier gas.) The clay remains intact at these reaction temperatures as evidenced from the thermal data (17). 

The cyclohexane contact time was 6.0 s and the weight hourly space velocity was in the range 1.0-3.0. Each sample was heated under a flow of hydrogen at 550°C prior to use of the catalyst. 

The mass balance for an isothermal transformation of a reactant A in a plug flow reactor operated at steady state can be established from Figure 2.2(a). This mass balance leads to the following relation between the contact time (r in h taken as the reverse of the weight hourly space velocity, for instance, in grams of reactant... 

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