Effect of hydrotreatment

Effect of Hydrotreater Feedstock Boiling Range on 100N VI... 

Two-Stage Hydrotreatment of Asphaltene in Australian Brown Coal Liquid Effects of Two-Stage Concept on Catalyst Deactivation (Changes of Catalyst Activations and Weight in the Repeated Runs")... 

Fig. 14. Effect of decationizing pretreatment on the liquefaction, (a I) First-stage noncata-lytic hydrogen-transferred Morwell coal in the two-stage hydrotreatment (4(X)°C-10 min, 20 atm N>, tube bomb and molten tin bath, rapid heating) 4HFI/coal = 3.0g/3.()g. (a2) Second-stage catalytic hydrotreated Morewell coal in the two-stage hydrotreatment (400°C-20 min, 50 cc autoclave, slow heating).

Figure 2. Effect of oil concentration in supercritical hydrotreatment of arabian topped crude.

Figure U. Effect of temperature on supercritical hydrotreatment of shale oil.

FIGURE 23.7 Effect of pressure upon thiophene conversion during hydrotreatment. Simulation temperature 553 K. (a) Thiophene conversion at network centerplane. (b) Fraction of pores on a percolating path to the pellet surface. The line is shown to guide the eye error bars represent the spread in thiophene conversion values resulting from simulations performed upon 5 separately generated pore networks. (From Wood, J., Gladden, L.F., and Keil, F.J., Chem. Eng. ScL, 57, 3047-3059, 2002. With permission.)... 

In this chapter, the effect of capillary condensation upon catalytic reactions in porous media has been reviewed. It was shown that capillary condensation could have a strong influence upon catalytic reactions on its kinetics, transient dynamics, and catalyst pellet effectiveness factor. The reaction rate in the liquid phase is usually slower than in the gas phase due to the difference in adsorption equilibrium, and due to low solubility of hydrogen in the liquid (in hydrotreatment processes). 

Ahmed, M.M. and B.L. Crynes. Coal Liquids Hydrotreatment-Catalyst Pore Size Effects. Preprints of ACS Symposium on Effect of Pore Size on Catalytic Behavior. Florida 23(4) (1978) 1376. 

We first looked at the effect of varying the amount of hydrotreated material in an FCC feed blend from 0.0 to 96.7 vol%. Table 10 presents selected process conditions for the feed hydrotreater, which achieved 90% desulfurization and roughly 23 wt% conversion of vacuum gas oil to middle distillate and naphtha. 

With these four vacuum residua it is possible to evaluate the effect of the type of feed to the gasifier, and also the effect of using a VR coming from crude oil hydrotreatment. The results of the simulation using these four feeds at identical operating conditions are reported in Table 4.7. 

In the reverse flow type, the hydrotreater reactor is fed with fresh and recycled feeds, and is operated to accomplish partial conversion of that combined feed in the first stage. A graded HDT-HCK bed or a multi-functional catalyst can be used in the first stage. A very effective H2 separation is used for the first-stage effluent gas. A bottoms fractionator or an adsorption unit is used for removal of heavy PAHs. Carbon adsorption extends the catalyst life. The liquid product of the first reactor is mixed with a mixture of fresh and recycled H2. The whole second stage effluent is hydrotreated in the first stage. 

The desulfurization process reported by the authors was a hybrid process, with a biooxidation step followed by a FCC step. The desulfurization apparently occurs in the second step. Thus, the process seems of no value, since it does not remove sulfur prior to the FCC step, but only oxidizes it to sulfoxides, sulfones, or sulfonic acids. The benefit of such an approach is not clearly outlined. The benefit of sulfur conversion can be realized only after its removal, and not via a partial oxidation. Most of the hydrotreatment is carried out prior to the FCC units, partially due to the detrimental effect that sulfur compounds exert on the cracking catalyst. It is widely accepted that the presence of sulfur, during the regeneration stage of the FCC units, causes catalyst deactivation associated with zeolite decay. In general terms, the subject matter of this document has apparent drawbacks. 

Consent decrees may specify hardware or additive solutions for individual applications. When a refiner agrees to implement a hardware solution, emissions limits are typically specified in the Consent Decree. This requires the refiner to design and implement an appropriately sized unit to meet these limits. With FCC additive solutions or hybrid solutions combining hardware and additives (such as a hydrotreater and SOj reduction additive), final emissions limits are not generally defined in the Consent Decree. Instead, a testing and demonstration program is defined to determine the performance of the additive(s) in the FCC unit at optimized concentrations. This may also be the case for some hardware solutions. The process to determine the optimized additive rate and process conditions is also identified. A baseline period and model is often used to determine additive effectiveness. A series of kick-out factors based upon additive performance are evaluated to determine the optimized level... 

Flue gas scrubbing also has high capital and operating costs associated with it, but also offers PM control. An additive-only solution is almost always the least expensive option when including both capital and operating expenses for SO, reduction depending on the feed sulfur. SO, reduction additives can also be effectively used in conjunction with one of the other solution options. For example, several refiners with FCC feed hydrotreaters use a SO, reduction additive to trim the SO, emissions to the required 25 ppm level rather than to hydrotreat the FCC feed more severely or to install a flue gas scrubber. The optimum choice for a given unit is often site specific. 

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