LHSV

In 1997, UOP announced the PX-Plus process which also uses a selectivated catalyst to convert toluene to para-rich xylenes. Pina commercialized a TDP process known as the (T2PX) process in 1984 (70). It uses a proprietary catalyst to react toluene at 42—48% conversion with selectivities to benzene of 42 wt % and to xylenes of 46 wt %. The xylenes produced are at equiUbrium. Typical commercial operating conditions of 390—495°C, H2 partial pressure of 4.1 Mpa, H2/hydrocarbon molar ratio of 4 1, and LHSV of 1—2/h. Pina s first commercial implementation occurred in 1985 at their Port Arthur refinery. 

UOP s Isomar process (56,117—119) was originally developed to use dual-functional catalysts. The first-generation catalyst contained Pt and halogen on alumina. Operating conditions using this catalyst were 399°C 1.25 MPa 2 LHSV and H2/hydrocarbon ratio of 6 1. A Cg naphthene concentration of... 

C and 6.9 MPa (70.3 kg/cm ) in 100% selectivity (113). The neoalcohol was also produced in selectivities of 99% by employing zirconium hydroxide catalysts (114,115). The rates of the latter process, however, are reportedly low at Hquid hourly space velocity (LHSV) of <1 kg/catalyst-h. A catalyst from... 

The quantity of catalyst used for a given plant capacity is related to the Hquid hourly space velocity (LHSV), ie, the volume of Hquid hydrocarbon feed per hour per volume of catalyst. To determine the optimal LHSV for a given design, several factors are considered ethylene conversion, styrene selectivity, temperature, pressure, pressure drop, SHR, and catalyst life and cost. In most cases, the LHSV is ia the range of 0.4—0.5 h/L. It corresponds to a large quantity of catalyst, approximately 120 m or 120—160 t depending on the density of the catalyst, for a plant of 300,000 t/yr capacity. 

LHSV (liquid hourly space velocity) = (volume of liquid feed at 60°F/h)/(fF of reactor) = SCFH hquid feed/fF. 

Butadiene sulfone (butadiene, SOci) CST L f-Butyl catechol 34 12 0.2 LHSV [1]5 192... 

Cracking (visbreaking residual oils) TU LG None 470-495 10-30 450 s, 8 LHSV [11]... 

Methyl ethyl ketone (2-Lutanol) FB G Brass spheres 450 5 2.1 s 13 LHSV [10] 284... 

Allyl alcohol (propylene oxide) FB G Li phosphate 250 1 1.0 LHSV (15) 2.3... 

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. 

In most applieations, the reaetion oeeurs between a dissolved gas and a liquid-phase reaetant in the presenee of a solid eatalyst. In some eases, the liquid is an inert medium and the reaetion takes plaee between the dissolved gases at the solid surfaee. These reaetors have many diverse applieations in eatalytie proeesses and are used extensively in the ehemieal industry. Triekle-bed reaetors have been developed by the petroleum industry for hydrodesulfurization, hydroeraeking, and hydrotreating of various petroleum fraetions of relatively high boiling point. Under reaetion eonditions, the hydroearbon feed is frequently a vapor-liquid mixture that reaets at liquid hourly spaee veloeities (LHSV in volume of fresh feed, as liquid/volume of bed, hr) in the... 

The reactor feed may be preheated and the feed pressure may alter. The volumetric flowrate of gases depends on the reactor temperature and pressure at fixed mass flowrate. In many cases, the feed is liquid at room temperature, while the reaction mixture is a gas at the higher temperature in the reactor. In these instances, the performance of the reactor is represented as conversion and selectivity against the liquid hourly space velocity (LHSV). This is defined as... 

LHSV Temp.,°F % Conversion Selectivity to Benzene Selectivity to Isohexane... 

Normally, catalytic reformers operate at approximately 500-525°C and 100-300 psig, and a liquid hourly space velocity range of 2-4 hr" Liquid hourly space velocity (LHSV) is an important operation parameter expressed as the volume of hydrocarbon feed per hour per unit volume of the catalyst. Operating at lower LHSV gives the feed more contact with the catalyst. 

Methanol conversion to hydrocarbons over various zeolites (370X, 1 atm, 1 LHSV)... 

A vapor phase process for deparaffmization of light gas oils performed by the BP works in this way The gas oil, boiling range 230-320°C, is passed over a 5-A molecular sieve at 320°C and a pressure of 3.6 bar. The space velocity is 0.63 vol liquid gas oil per vol molecular sieve and per hour, [liquid hourly space velocity (lhsv) = 0.63] the adsorption period takes 6 min. Together with the gas oil vapor 120 vol N2 per vol liquid gas oil is led over the sieve as carrier and purge gas. After the adsorption period the loaded molecular sieve is purged at the same temperature with pure N2 for 6 min. Subsequently, the adsorbed /z-alkanes are desorbed by 1 vol liquid /z-pentane per vol molecular sieve and per hour. The /z-pentane is recovered from the /z-alkane//z-pentane mixture by simple distillation [15]. The IsoSiv process of the Union Carbide Corporation works in a similar way [16]. The purity of the isolated /z-alkanes is >98%. 

Weight percent profiles through first-stage (left) and second stage reactor of a) alkanes (full fines) and cycloalkanes (dashed fines) and b) aromatic components. Thick lines correspond to C23 finctions, thin lines to 23 fractions. Operating conditions p, 17.5 MPa LHSV 1.67 niL (nv hf molar H2/HC 18 Tmiei 661 K (reactor 1) 622 K (reactor 2). Catalyst NiMo on amorphous silica-alumina. 

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