Catalysis of Organic..

O’Keefe, Jiang, Ng and Rempel 369conditions to provide narrow 95% confidence intervals and hence precise estimatesof the reboiler product composition. For example, the reboiler compositioncorresponding to the second condition in Table 1 was based on 6 steady stateobservations. The resultant 95% confidence intervals for the mesityl oxide and DAAmass fractions for this entry correspond to relative errors of 1.44 and 1.73 %respectively.The hydrogenation catalyst activity was tested before and after the CDexperiment in a 300 mL Parr 4560 series microreactor with a Parr 4842 PIDcontroller. Liquid samples were obtained periodically through a dip-tube with acustom made external heat exchanger and analyzed by GC/FID. The hydrogenationcatalyst was characterized by Diffuse Reflectance Infrared Fourier Transform(DRIFT) spectroscopy. The adsorption properties of MIBK, mesityl oxide, acetoneand carbon monoxide probe molecules on the Pd/Al 2 O 3 catalyst were investigatedusing an Excalibur Bio-Rad FTIR spectrometer equipped with an MCT detector. Theheat treatment and reduction of the catalyst as well as the adsorption and desorptionof probe molecules were investigated in situ in a high temperature IR cell equippedwith a ZnS dome while DRIFT spectra were recorded in 10s intervals.Results and DiscussionPilot Scale CD ExperimentsIn the first experiment, Amberlyst-15, a strongly acidic cation exchange resin, wasused as a catalyst to synthesize mesityl oxide, the precursor of MIBK, from acetonewithout hydrogenation. The effects of acetone feed rate, reboiler duty and reactiontemperature on the mesityl oxide productivity and product distribution wereinvestigated. Preliminary results of this experiment are outlined in Table 1.Table 1. The effects of reaction temperature, acetone feed rate and reboiler duty onthe mesityl oxide productivity and product distribution for the first CD experimentAcetoneFeedRate[mL/hr]ReactionTemp[°C]ReboilerDuty[Watts]AcetoneConv.[%]MOProductivity[g/hr*mL cat]MO[wt%]DAA[wt%]HigherMwt[%]152 114 300 26.2 .1418 19.0 1.31 1.72152 114 350 26.7 .1601 18.6 1.81 0.89152 101 350 29.0 .1788 19.5 3.73 0.2437 99 350 >99.9 .1413 78.2 a 14.2 0.95a Last condition is a preliminary result. Process had not yet achieved steady stateafter 24 hours. Two phases present, composition for organic phase is reportedIt was found that the mesityl oxide productivity was a strong function of the refluxflow rate in the CD column, which suggests the reaction is controlled by the rate ofexternal mass transfer. It is also evident from Table I that acetone conversions ashigh as essentially 100% can be achieved with the mesityl oxide concentration in the