High throughput development method for catalytic hydroprocessing of dirty feedstocks

Abstract

A method for determining a set of operating parameters for a commercial scale plug flow catalytic process and reactor system for hydroprocessing dirty feedstocks, comprises the steps of: feeding selected partial pressures of said feedstock and hydrogen to the inlet the first reactor stage of a first composite multi-stage series-connected laboratory scale plug flow reactor including at least three reactor stages, the catalyst beds of each of said reactor stages including catalyst particles capable of catalyzing the removal by hydrogen of heteroatoms from said heterocyclic molecules; sampling the effluents of each of said reactor stages; measuring the concentration of heterocyclic molecules in said dirty feedstock in the concentrations of heterocyclic molecules and intermediate and final products and by products of the catalytic reaction in the effluents of each of said reactor stages.

Description

FIELD OF INVENTION[0001]This invention relates to methods for the low cost, accelerated development from discovery to commercial readiness of catalysts and plug flow catalytic processes for hydroprocessing of dirty feedstocks. By the term “dirty feedstocks” is meant feeds such as C10-C20+ distillates from crude oil that contain large heteroatom containing molecules, and cycle oils produced in refinery operations.BACKGROUND OF THE INVENTION[0002]In order to scale-up a plug flow catalytic process for hydroprocessing of dirty feedstocks, it is necessary to define the impact of feedstock composition, time on stream, residence time, catalyst particle size, shape and other characteristics, and temperature profile on reaction rate and selectivity. The first step in a traditional scale-up program generally involves the selection, and definition of the intrinsic properties of, the catalyst. This step is typically performed isothermally with a diluted, crushed or powdered catalyst to minimize...

AI Technical Summary

Benefits of technology

[0014]This invention relates to a low cost, accelerated method for determining an advantageous combination of reactor structures, catalyst characteristics, catalyst bed structures and process conditions for scaling up from discovery to commercial readiness a plug-flow catalytic process and reactor system for hydroprocessing dirty feed stocks, and having high productivity and selectivity to desired products.

[0015]The method of the invention involves the use of high throughput laboratory scale catalytic process development apparatus that includes multistage series-connected laboratory scale plug-flow reactors to iteratively investigate each of the separate successive hydroprocessing steps performed on the dirty feed stocks, including removing heteroatoms, saturating polynuclear aromatics, cleaving carbon-carbon bonds in cyclic molecules, saturating unsaturated molecules, and hydrocracking and isomerizing the resulting hydrocarbon molecules. The characteristics and compositions of the effluents of the laboratory scale reactor stages are sampled and measured during each iteration, and the results of such measurements made during one iteration are used to help determine the choice of catalyst bed characteristics and process conditions in subsequent iterations for improving the productivity and selectivity of hydroprocessing operation.

[0017]The data generated as a result of this testing enables the design of a commercial scale plug-flow catalytic process and reactor system for hydroprocessing dirty feed stocks in which the catalyst characteristics and operating parameters, including partial pressures of reactants and products, temperatures, pressures and flow rates are optimized. Thus, in accordance with the method of the invention, the longitudinal gradients in kinetics, mass transfer and heat transfer characteristics for the various reactions occurring within the catalyst beds, or catalyst bed segments, for each of the upgrading steps for hydroprocessing dirty feedstocks in a commercial scale reactor or reactors are investigated with the use of composite multistage series-connected laboratory scale fixed bed reactors that effectively permit the segmenting of each individual catalyst bed, or bed segment, in the commercial scale reactors into successive longitudinally distributed slices to permit the taking of measurements to investigate the kinetic, mass transfer and heat transfer characteristics for the different chemistries occurring within each of such slices of the catalyst beds or bed segments. The data gathered based on these measurements allows the development of predictive models using laboratory-scale reactors that describe the behavior is applicable to large-scale catalytic hydroprocessing systems.

Problems solved by technology

The larger particle size generally results in a lower reaction rate and a selectivity loss due to limitations on mass transfer of reactants or products in and out of the catalyst pores.

While this issue is very important for a full understanding of HDS mechanisms and processes, it has not been adequately and quantitatively addressed in the open HDS literature, although many HDS studies have been conducted separately with either full-size catalysts or crushed catalyst particles.

This sequential approach typically takes in excess of three years to complete and may not provide all of desired data for scale-up.

Despite the relatively large number of patents covering the different unsupported catalysts and their applications in hydroprocessing, there are only a few commercial bulk hydrotreating catalysts.

However, incorporating a catalyst with extremely high activity in existing refinery process equipment is all but straight forward.

In many cases the process and the equipment was not designed for the heat release and H2 consumption accompanying a very high activity catalyst.

High concentration of metals and higher density of unsupported, as compared to supported, catalysts will increase the reactor fill price significantly.

Consequently, there are only limited offerings of commercial bulk hydroprocessing catalysts, with one being sold in sizable amounts in the present hydroprocessing market.

This approach is useful for comparing the intrinsic properties of an array of candidate catalysts but does not provide the data required for scale-up.

This approach is limited because, at least for a number of exothermic and endothermic catalytic reactions, it is difficult to correlate the results obtained on this small scale with those obtained on a commercial scale.

This limitation exists, in part, because the heat transfer obtained on such a small scale cannot reasonably be correlated with what would be observed in a large reactor.

Here too, the approach is one that is unable to adequately address the full range of scale up issues including both heat and mass transfer effects on a commercially relevant scale of catalyst operation.

A small scale reaction which provides an acceptable product mixture may provide an unacceptable level of secondary reactions on scale-up due to heat and or related mass transfer effects.

Thus, it is quite difficult to extrapolate the results on small scale endo-thermic reactions to large commercial scale reactors.

At the same time, it is not possible to take advantage of High Throughput combinatorial chemistry with the use of commercial scale reactors.

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