Catalysis of Organic..

368 MIBK Synthesis via CDExperimental SectionThe pilot scale experiments were carried out in a CD column 23 ft (7 m) tall with atotal packing height of 16 ft (4.9 m) and a 1” (2.54 cm) nominal I.D. The column ismade of 316 SS and consists of 5 sections that are connected by flanges. Two 2 ft(0.6 m) sections located above a 9 ft (2.7 m) stripping section and below a 3 ft (0.9m) rectification section, were used as the reaction zones, which contained thecatalyst. The non-reactive sections were filled with ¼ inch (0.64 cm) Intalox saddles.In the first experiment for which mesityl oxide was synthesized from acetone, thetwo sections were filled with 130 mL of Amberlyst-15, that had been swelled in 2-propanol for 24 hours, in wire mesh bundles. In the second experiment in whichMIBK was synthesized from acetone, the top section and the top half of the bottomsection contained 135.0 mL of Amberlyst-15 in wire mesh bundles that had beenswelled in acetone for over 24 hours. The bottom half of the bottom section,immediately below the Amberlyst 15, was filled with 50.1 g of a commercialPd/Al 2 O 3 catalyst (Aldrich 20,574-5). The hydrogenation catalyst was reduced exsitu in hydrogen at 350°C for 3 hours and was transferred to the CD column under anitrogen blanket.The CD column was operated in continuous mode with 100% of the overheadproduct being refluxed to the column and a reboiler product stream was continuouslyremoved from the bottom of the column through a control valve. ACS reagent gradeacetone (Aldrich 67-64-1, >99.5%) was fed continuously to the CD column at a feedport approximately 6 in. (15 cm) below the bottom of the reaction zone using aMilton-Roy LCD mini pump. The reboiler product stream mass flow rate wasmatched the acetone feed stream by maintaining a constant liquid level in thereboiler. In the first experiment, nitrogen was fed to the CD column to promote theconvective transport of matter and energy up the column. In the second experiment,UHP Hydrogen was fed continuously to the bottom of the CD column using aBrooks 5850E mass flow controller (MFC) instead of nitrogen. Liquid samples wereobtained from the reboiler product on an hourly basis and the average reboilercomposition for the previous hour was ascertained by GC/FID using an AgilentTechnologies 6890N gas chromatograph equipped a 7683 Series autosamplerinjector and a J&W Scientific DB-WAX column (30m X 0.53mm I.D. X 1mm filmthickness). Certified 1-Propanol (Fisher A414-500 >0.998) was used as an internalstandard. Data was acquired continuously from the CD column including thecolumn temperature profile measured at 16 thermocouple locations along the columnmajor axis, the column pressure and the pressure drop across the column in additionto the hourly reboiler product composition. Since the reaction zones are shortrelative to the total column height, the thermal profiles along the reaction zones wereisothermal during steady state operation. Steady state was defined as the conditionwhere the CD column temperature profile remained invariant to within ± 0.5 °C andthe mass fraction of species in the reboiler product remained constant to within amaximum relative change of ± 5%. Once steady state had been achieved, the steadystate condition was maintained from 5 to 10 hours depending on the processvariability, during which time, sufficient observations were made under steady state