Paraffins conversion catalysts

Light hydrocarbons (Ci to C4) and aromatics (mainly Ce to Ce) were produced by ZSM-5 due to the the conversion of olefins and paraffins. Thus,these results provide evidence for cracking of olefins, paraffins and cyclization of olefins by ZSM-5 at 500 C. The steam deactivated ZSM-5 catalyst exhibited reduced olefin conversion and negligible paraffin conversion activity. 

Paraffin conversion to naphthenes is very unfavorable (last column of Table IV). For paraffins to be converted to naphthenes by ring closure, naphthenes must be at very low concentrations. If appreciable naphthenes exist, such as at short catalyst contact times, naphthene ring opening to paraffins can occur. Again, equilibria improve with carbon number. Eight-and nine-carbon paraffins behave quite similarly. 

Fig. 24. Coke yield versus shape selectivity of paraffin conversion for various zeolite catalysts. (Reproduced from Ref. 266 with permission from the authors.)...

The PACOL process (paraffin conversion to olefin) produces n-olefins by dehydrogenation of paraffin over a heterogeneous platinum catalyst. The Pacol process is more selective than thermal cracking and produces smaller amounts of byproducts. 

The rate of light paraffin conversion over a Pt catalyst (Oleflex type process) can be expressed as a... 

This catalytic system, as well as systems based on Mo/V/Te/Nb mixed oxides which have been developed by Mitsubishi (65), also represent an example of catalyst characterized by multifunctional properties. The rutile structure is the matrix to host vanadium ions as solid solutions, while the antimony oxide is present as a dispersed microcrystalline oxide. Vanadium is the component which is more active in paraffin conversion, while the high selectivity to the desired product is due to the presence of dispersed, separate phase, antimony oxide. 

Table 3 shows the catalytic properties of these samples. One can see from the data, that all catalysts synthesized on the basis of the mechanochemically treated V2O5 show an increased selectivity towards maleic anhydride and higher specific rate of n-butane and n-pentane oxidation as compared to those obtained in traditional synthesis. The best effect in the improvement of selectivity can be reached by increase of the relative exposure of (001) plane at the VOHPO4.O.5.H2O surface which is known to be transformed into (200) plane of (VO)2P207. The low paraffins conversion over VPO-E samples at the given reaction conditions can be directly connected with their low specific surface area. The comparison made between samples VPO-El and VPO-E2 shows that the precursor synthesis using V2O5-E needs to be optimized in order to improve the catalytic performance. 

Compared to SMDS, this simplified process employs a different catalyst in the synthesis stage and does not include a Heavy Paraffinic Conversion stage for producing the finished middle distillate fractions. The syncrude product is a broad boiling range of hydrocarbons (Table 4), and the relative amounts of individual products can be varied by adjusting the reaction conditions. Alternatively, syncrude products can be processed in existing refineries into finished transportation fuels. 

Shape selective catalysis with molecular sieve zeolites has progressed in its first thirty years to become an established branch of catalytic science. Since the first demonstration of selective n-paraffin conversion over 5A molecular sieves, increased insight into how these catalysts function has created opportunities for the development of a number of new industrial processes. 

Paraffin conversion to valuable BTX products over HZSM-5 catalyst is due to... 

The dehydrogenation of n-heptane over a platinum-low acidity catalyst was also investigated. Owing to the lower molecular weight of n-heptane, somewhat higher temperatures (<— 20°C) were required to achieve paraffin conversions similar to those obtained with n-dodecane. However, at these slightly higher temperatures, product distributions and selectivities were close to those found with n-dodecane. 

The plant includes hydrocracking of the LTFT products over a dual functional catalyst in the Heavy Paraffins Conversion (HPC) unit. The products of the SMDS Bintulu plant include naphtha, kerosene, diesel and some fuel gas. The HPC unit is operated t5q)ically at 30-50 bar total pressure and at a temperature of about 300-350°C, actually performing four functions ... 

The Heavy Paraffin Conversion process has now been developed to convert the heavy paraffins selectively into the desired middle distillates, kerosine and gas oil. It is a mild hydrocracking process using a dual functional (Shell proprietary) catalyst. 

The performance of a new Pt-Sn/slit-SAPO-34 catalyst in selective Cj-C dehydrogenation to light olefins [76] was shown to be optimal at an atmospheric pressure, hydrogen to alkane molar ratio of 0.2, weight hourly space velocity of 5 h and temperature about 585°C. The light paraffin conversion as high as 40% and the total olefin selectivity above 95% were achieved over Pt-Sn/slit-SAPO-34. 

Figure 18.15 Selectivity to C4—Cg isoparaffins at 40% total n-paraffin conversion over microporous/mesoporous Pt/ZSM-5 catalysts (reaction conditions P = 30 bar ...

Mobil s High Temperature Isomerization (MHTI) process, which was introduced in 1981, uses Pt on an acidic ZSM-5 zeoHte catalyst to isomerize the xylenes and hydrodealkylate EB to benzene and ethane (126). This process is particularly suited for unextracted feeds containing Cg aHphatics, because this catalyst is capable of cracking them to light paraffins. Reaction occurs in the vapor phase to produce a PX concentration slightly higher than equiHbrium, ie, 102—104% of equiHbrium. EB conversion is about 40—65%, with xylene losses of about 2%. Reaction conditions ate temperature of 427—460°C, pressure of 1480—1825 kPa, WHSV of 10—12, and a H2/hydtocatbon molar ratio of 1.5—2 1. Compared to the MVPI process, the MHTI process has lower xylene losses and lower formation of heavy aromatics. 

C with low conversion (10—15%) to limit dichloroalkane and trichloroalkane formation. Unreacted paraffin is recycled after distillation and the predominant monochloroalkane is dehydrochlorinated at 300°C over a catalyst such as nickel acetate [373-02-4]. The product is a linear, random, primarily internal olefin. 

Mobil MTG and MTO Process. Methanol from any source can be converted to gasoline range hydrocarbons using the Mobil MTG process. This process takes advantage of the shape selective activity of ZSM-5 zeoHte catalyst to limit the size of hydrocarbons in the product. The pore size and cavity dimensions favor the production of C-5—C-10 hydrocarbons. The first step in the conversion is the acid-catalyzed dehydration of methanol to form dimethyl ether. The ether subsequendy is converted to light olefins, then heavier olefins, paraffins, and aromatics. In practice the ether formation and hydrocarbon formation reactions may be performed in separate stages to faciHtate heat removal. 

UOP Inc. is the key source of technology in this area, having numerous patents and over 70 units operating worldwide (12). The dehydrogenation catalyst is usually a noble metal such as platinum. Eor a typical conversion, the operating temperature is 300—500°C at 100 kPa (1 atm) (13) hydrogen-to-paraffin feed mole ratio is 5 1. 

Dehydrocyclization refers to the conversion of feed paraffins into alkylcyclohexane and alkylcyclopentane naphthenes. These, in turn, are subsequently converted by isomerization and dehydrogenation into aromatics. Dehydrocyclization is controlled by both acid and platinum functions and is the most sensitive indicator of catalyst selectivity. 

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