Mild hydrocracking

The HCR reaction was represented by a three-lump model as follows (Bhaskar et al., 2004)  

Light gasesGas oil— NaphthaLight gases (hydrocarbon gases like Ci - C4) 

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Mild hydrocracking prepares the feedstock for catalytic cracking or for the conventional lubricant production scheme. 

Table 10.18 presents some useful data on the mild hydrocracking process and resulting products. 

Typical Feedstocks composition, performance and product properties from mild hydrocracking. I... 

More severe hydrotreating, such as mild hydrocracking at an H2 partial pressure of >6.9 MPa (1000 psig) and temperature of >400° C, can stiU further reduce sulfur content in the FCC feed. Mild hydrocracking of a 25° API VGO reduced the sulfur content of the FCC feed 98%, from 1.7 wt % to 0.03 wt % (40). This reduction can be expected to lower the SO content in the FCCU regenerator flue gas by about 90%. 

This work is a contribution to the understanding of the effect of spillover hydrogen in a type of catalyst of considerable industrial importance, namely that composed of transition metal sulfides and amorphous acidic solids. This is typically the case of sulfided CoMo supported on silica-alumina used for mild hydrocracking. 

Dieselmax A petroleum cracking process which combines mild hydrocracking with thermal cracking to maximize the production of middle distillate without using more hydrogen than hydrocraking alone. Developed by UOP. 

MHC Unibon [Mild hydrocracking] A mild hydrocracking process for desulfurizing gas oil and converting it to lower molecular weight hydrocarbons, suitable for further processing by catalytic cracking. Developed by UOP. 

The Axen s mild hydrocracking process combines an ebullated-bed, mild hydrocrack-... 

As to the acidic functions mentioned in Table 6.2, alumina, even after fluoridation (11), is obviously the least active in cracking. But since alumina is such an excellent support for the hydrotreating function, these catalysts do have merits in hydrocracking of e.g. nitrogen-rich feeds, as in mild hydrocracking. 

Fina developed the technology which was practiced in their own refineries before they decided to license it in cooperation with Akzo Nobel to other companies. Akzo Nobel has successfully marketed the technology with eleven licenses sold today in Europe, North America and Japan. The process scheme is identical to typical hydrotreating units. Process conditions are similar to what is practiced in LGO or VGO hydrotreating or mild hydrocracking units. Catalysts applied in the process are only available under license. 

Mild hydrocracker to produce middle distillates from heavy feedstocks at high temperatures. 

The middle distillate yield is almost constant during the Mild Hydrocracking mode of operation, except at the end of the run. 

In mild hydrocracking of atmospheric residue for maximum middle distillates production, the metal tolerance of the demetallization catalyst is the most important factor determining the catalyst life. The deactivation by metals is the prevailing mechanism in this mode of operation. 

ARDS unit works as the springboard in the new scheme of Mina Abdulla Refinery operation Primarily a desulfurization unit, ARDS also reduces the metals, asphaltenes and nitrogen in the products, thereby, ensuring proper quality of feed for downstream conversion units. As an additional benefit, ARDS is also a mild hydrocracking process, partially upgrading high sulfur atmospheric residue to low boiling products like naphtha and distillate. 

In addition to the above, mild hydrocracking associated with the process leads to production of Distillate and Naphtha thus helping upgradation / optimization of refinery product slate. 

In comparison to zeolites, ordered mesoporous materials overcome the pore-size constraint of zeolites and allow easier diffusion of bulky substrates. Unrestricted diffusion of reactants and products for mesoporous materials was observed even after the incorporation of large catalytically active sites in the mesopore system. Ordered mesoporous oxides have been used as supports for metals and metal oxides, and as a host material for anchoring stereo- and enantio-selective species. In reactions that require milder acidity and also involve bulky reactants and products, such as mild hydrocracking reactions, mesoporous materials exhibit great potential.[40,296]... 

The mild hydrocracking process uses operating conditions similar to those of a VGO desulfurizer to convert VGO to yield significant lighter products. Consequently, the flow scheme for a mild hydrocracking unit is virtually identical to that of a VGO desulfurizer. 

As illustrated earlier, for various forms of more conventional hydrocracking, the type of catalyst used can influence the product slate obtained. For example, for a mild hydrocracking operation at constant temperature, the selectivity of the catalyst varies from about 65% to about 90% by volume. Indeed, several catalytic systems have now been developed with a group of catalysts, specifically, for mild hydrocracking operations. Depending on the type of catalyst, they may be run as a single catalyst or in conjunction with a hydrotreating catalyst. 

Zeolites are hydrated alumino-silicates and are used widely in the chemical and environmental industries. Their activity is influenced by the ratio of silica to aluminum. Amorphous silica-alumina catalysts have a lower activity than zeolitic catalysts and are used in mild hydrocracking reactions where acidic surfaces are required. The acidity is maintained by oxygen atoms attached to the aluminum atoms. 

Many catalytic applications have been proposed [71, 72]. Mobil announced in 2004 that a mesoporous catalyst was implemented on an industrial plant, but details on the nature of the application are still lacking at the moment in which this notes are written. Hydrotreating or mild hydrocracking processes seem to be the most likely candidates. 

Tn synthesizing low sulfur fuels from coal the Stone Webster process A uses the step-by-step addition of hydrogen to coal under conditions which minimize coke production. The first step involves the conversion of solid coal to a liquid by mild hydrocracking in the presence of a recycle solvent. In the next step these liquids react further with hydrogen under more severe conditions to produce methane, ethane, and aromatics. 

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