Microactivity testing

The microactivity test uses small quantities of catalyst, only 4 grams, and a feed of 1.33 g in 75 seconds, so it is a very fast test, but the test s empirical usefulness is strictly limited to one well-known technology, for an endothermic reaction and one very limited type of catalyst. 

Figure 2.2.1 shows the simplified sketch of the reactor used for the microactivity test. As can be seen, a fluid-bed catalyst is tested in a fixed bed reactor in the laboratory to predict its performance in a commercial fluid bed reactor. This can be done only because enormous empirical experience exists that has accumulated throughout several decades in several hundreds of reactors both in production and in laboratories. The standard states ... 

The microactivity test provides data to assess the relative performance of fluid cracking catalysts. ... 

Microactivity Test (MAT) is a small, packed-bed catalytic cracking test that measures activity and selectivity of a feedstock-catalyst combination. 

Except for the results reported in Table III, all catalytic activity and selectivity results were obtained using a microactivity test (MAT), ASTM D-3907-80. 

Analysis of two nickel-containing DFCC revealed that neither heating in air or in steam induced intraparticle transfer of nickel at the thermal and hydrothermal conditions used to age the fresh catalysts (11) prior to microactivity testing. 

Catalytic evaluations were conducted using microactivity tests (MAT) ( ) at 910 F initial temperature, 15 WHSV, 6.0 g catalyst, and a 5.0 cat-to-oil ratio. The feedstock was a metals-free mid-continent gas oil. Each data point shown is the average of two MAT runs. Only MAT runs with acceptable mass balance were used (96 to 101%). Additionally, MAT data was normalized to 100% mass balance. Extensive error analysis of conversion, coke, and hydrogen yields indicates the following respective standard deviations 1.62, 0.29, 0.025. The effects of nickel and vanadium on the hydrogen and coke make were calculated by obtaining the difference between the yields obtained with uncontaminated catalysts and that of the contaminated catalyst at the same conversion. 

When rare earth Y-zeolite (REY) was added to the PILC or to the parent clay, the dried PILC or "as received" clay was reslurried in water and the calcined REY added to the 10 wt % level. This slurry was then mixed, filtered, dried, and calcined at 500 C for 2 hours in air. The calcined REY was obtained from Union Carbide and contained 14.1 wt % rare earth elements, primarily lanthanum and cerium. Portions of the PILC were pretreated by one of the methods listed below prior to the microactivity testing. 

The catalyst used in this study corresponds to a fresh commercial catalyst used in one FCC unit of ECOPETROL S.A. This solid is hydrothermal deactivated at the laboratory in cycles of oxidation-reduction (air-mixture N2/Propylene) at different temperatures, different times of deactivation, with and without metals (V and Ni), and different steam partial pressures. Spent catalysts (with coke) are obtained by using microactivity test unit (MAT) with different feedstocks, which are described in Table 10.1. 

Catalytic evaluation of the different pillared clays was performed using a microactivity test (MAT) and conditions described in detail elsewhere (5). The weight hourly space velocity (WHSV) was 14-15 the reactor temperature was 510 C. A catalyst-to-oil ratio of 3.5-3.8 was used. The chargestock s slurry oil (S.O., b.p. >354 C), light cycle oil (LCGO, 232 C < b.p. <354 C) and gasoline content were 62.7 vol%, 33.1 vol% and 4.2 vol% respectively. Conversions were on a vol% fresh feed (FF) basis and were defined as [VfVp/V ] x 100, where is the volume of feed... 

Table 2. Microactivity test results for several pillared clay catalysts after calcination in air at 400 C for lOh. The zeolitic cracking catalyst has been aoed for 5 hours at 760 C with 100% steam at 1 atm. ...

This ability is measured throughout the petroleum industry by a tool referred to as the microactivity test. 

FIXED-BED AND FLUIDIZED-BED TESTS In the fixed-bed test, a sample of cracking catalyst was contacted with an FCC feed in a manner similar to the standard microactivity test (MAT) prescribed by ASTM (10). One major difference was that the reactor temperature was increased from 900°F to 960°F to better simulate current commercial operations. 

At microactivity test conditions (MAT), the mechanism of vanadium migration has been found to be a gas-phase transport phenomena (20,23). However, a particle contact interaction mechanism has also been suggested (21). Formation of surface compounds, such as heat stable vanadates (5), may help explain V migration and V induced FCC deactivation. Few experimental investigations of metal migration between the various FCC components have been reported. 

Fig. 5.9 Effect of a V-trap on a commercial FCC catalyst (Ecat = Equilibrium Catalyst, MA = Microactivity test (7))...

Laboratory evaluation of the catalytic performance of fresh FOC catalysts involves steaming and activity testing. The latter is most often performed using a microactivity test (MAT). While there are other parameters that are important in comparing total performance of catalysts like attrition and fluidization, this paper... 

Catalytic Cracking Test. A standard microactivity test (MAT) was used to evaluate the conversion and selectivity of catalyst samples. The tests were done at the University of Pittsburgh s Applied Research Center (former Gulf Research Laboratory), a qualified laboratory for MAT evaluations. A standard method, developed by Gulf, was used without modification. A Cincinnati gas oil was cracked under the following conditions cat/oil=3, 16 h 1 WHSV, and 516°C. Prior to charging the reactor, all samples underwent a standard thermal pretreatment. Solids were first heat shocked for 1 h at 593°C. Next, selected materials were impregnated with 3000 ppm Ni and 6000 ppm V, as naphthenates. Then all samples were calcined for 10 h at 538°C. Finally, each material was steamed at 732°C for 14 h in a fluidized bed to produce a catalyst in a simulated equilibrium state. 

D-3907 Method for Testing Fluid Catalytic Cracking Catalysts by Microactivity Test Activity of FCC catalysts as evaluated by percent conversion of gas oil using a fixed bed reactor... 

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