Catalyst Deactivation Model

In AHYC, the catalyst deactivation model calculates the deactivation rate as function of the following  

The model predicts future catalyst activity, required temperature, yields, hydrogen consumption, and product properties. Alternatively, if the catalyst cycle hfe is fixed, the model can compute the optimal changes in feed rate, feed properties and/or conversion needed to reach the target end-of-run date. 

At the hydrocracker at Suncor Sarnia, the deactivation model is applied to each catalyst bed. This enables the development of strategies to bring all catalyst beds to end-of-run at (roughly) the same time, and prediction of future yields, selectivity and product properties. 

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Despite the increase in zeolite content, catalyst B deactivated faster than A requiring only four and a half hours to reach 66 FAI activity. Using our catalyst deactivation model which allows us to accurately translate laboratory catalyst deactivation to commercial make-up predictions (10), we estimate a much higher makeup rate is required for catalyst B to achieve the same activity as catalyst A (see Table I). 

The changing catalyst porous texture is modelled using a Bethe network originating from percolation concepts. Preliminary results indicate that reliable metal deposition profiles and catalyst life-time predictions can be made by the proposed catalyst deactivation model. 

As observed from simulations, the formulated HDM catalyst deactivation model based on the percolation approach can predict metal deposition profiles and catalyst life time. In the industrial application of hydrotreating catalysts metal deposition maxima are observed in spent catalysts, which is in qualitative agreement with the developed model... 

Key-issue in hydrodemetallisation (HDM) process design and operation is the development of catalyst deactivation models which give reliable predictions of catalyst life-time and activity, thus providing a tool for designing optimized catalysts. 

The general approach for modelling catalyst deactivation is schematically organised in Figure 2. The central part are the mass balances of reactants, intermediates, and metal deposits. In these mass balances, coefficients are present to describe reaction kinetics (reaction rate constant), mass transfer (diffusion coefficient), and catalyst porous texture (accessible porosity and effective transport properties). The mass balances together with the initial and boundary conditions define the catalyst deactivation model. The boundary conditions are determined by the axial position in the reactor. Simulations result in metal deposition profiles in catalyst pellets and catalyst life-time predictions. 

A Catalyst Deactivation Model for Residual Oil Hydrodesulfiirization and Application to Deep Hydrodesulfurization of Diesel Fuel... 

The catalyst deactivation model developed in this paper accounts for the nonsteady-state activity of commercial catalysts measured using accelerated sulfur aging experi-... 

Using the resin, asphalt (R+AT) and aromatics (AR) separated from an atmospheric rcsid oil (ARO) as fc stocks, we have investigated the effects of catalytic coke additive coke (Cgdd) on the cracking activity of a commercial FCC catalyst in a fixed bed (FB) and a rixed fluid bed (FFB) pilot units. Correlations between catalyst activity (a) and coke on catalyst (Q.) have been developed. A catalyst deactivation model, which is useful in modeling of cracking reaction kinetics, has been derived through rate equations of coke formation. 

A previously proposed state-of-the-art catalyst deactivation model, based on percolation concepts (5, 6), is proposed to tackle the problem of the changing catalyst porous texture (see Figure 2). 

The effect of a nitrogen containing compoxmd (7), i.e. quinoline, and the presence of HjS on the vanadium deposition is assessed. An attempt is made to predict the experimentally found vanadium deposition profiles by the catalyst deactivation model based on percolation concepts. Furthermore, the vanadium deposits are localised using HREM. 

Figure 2. Reaction Scheme for the Catalyst Deactivation Model...

Curtis, Application of a Catalyst Deactivation Model for Hydrotreating Solvent Refined Coal Feedstocks, Ind. Eng. Chem. Proc. Des. Dev., 22 ... 

To describe the kinetics of catalytic cracking the three lump model was used in combination with three different catalyst deactivation model. Overall gas oil cracking kinetic constants (k or k ) along with the decay parameters for the three decay models were determined for four feedstock-catalyst combinations. An example of these evaluations is presented in Table 4. 

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