https://pure.uva.nl/ws/files/1937496/1613_16979y.pdf

Bulky Diphosphite-Modified Rhodium Catalysts: Hydroformylation and Characterization

The coinage metals, copper, silver, and gold, have unique characteristics for selective oxidation catalysis, particularly for partial oxidation of alcohols and olefins. A basic understanding of surface chemistry at the molecular level can help facilitate the improvement of current catalytic processes and the designing of new catalytic systems. In this critical review, the current state of knowledge of these reactions is reviewed. First, both the experimental and theoretical methods necessary for understanding surface reactivity are discussed with a specific set of examples directly related to these reactions. Next the state of understanding of the surface chemistry of the oxidation reactions of alcohols and olefins on these three coinage metals is reviewed and the reaction pathways are compared. Clear relationships between the low pressure surface science studies and more practical catalytic conditions are illustrated. Finally, recent theoretical advances in this area are discussed as well as possible future directions in this field (132 references).

Unraveling molecular transformations on surfaces: a critical comparison of oxidation reactions on coinage metals

In this work a series of supported Ag catalysts was studied for propylene epoxidation with molecular oxygen as the oxidant. It was found that α-Al2O3 and CaCO3 were suitable supports for propylene epoxidation and that on the latter Ag particles between 400 and 700 nm gave the highest selectivity to propylene oxide (PO). Ball-milling treatment of the CaCO3 catalyst and promotion with NaCl resulted in improved catalytic performance. The highest PO selectivity (45%) was obtained on a ball-milled catalyst with a silver loading of 56 wt.% supported on CaCO3 and promoted with 1 wt.% NaCl (Ag(56)–NaCl(1)/CaCO3). The catalysts were tested with reactant flow rates of C3H6:O2:He = 5:10:15 cm3 min−1, a gas hourly space velocity (GHSV) of 1800 h−1, a reaction pressure of 0.3 MPa, and a reaction temperature of 533 K (260 °C). Addition of 500 ppm of ethyl chloride (EtCl) to the reactant gases enhanced the stability of the Ag(56)–NaCl(1)/CaCO3 catalyst. X-ray diffraction (XRD) of the Ag(56)–NaCl(1)/CaCO3 catalyst detected the existence of AgCl in the catalyst and ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy confirmed the presence of surface Ag+ species. Scanning electron microscopy showed a roughening of the Ag particles by the ball-milling treatment as well as by the addition of NaCl. The effect of NaCl on the enhancement of the catalytic performance was probably due to both physical and electronic changes in the properties of the catalyst. The NaCl not only helped increase the dispersion of the silver on the CaCO3 support, but also probably increased the quantity of electrophilic oxygen species favorable for epoxidation. In situ UV–vis spectra suggested that the rapid reduction of Ag+ species on the surface of the Ag(56)–NaCl(1)/CaCO3 catalyst could be the cause of a decline in PO selectivity observed during reaction.

Direct propylene epoxidation over modified Ag/CaCO3 catalysts

The invention features methods for producing isoprene from cultured cells. The invention also provides compositions that include these cultured cells.

Compositions and methods for producing isoprene

http://iglesia.cchem.berkeley.edu/Publications/JournalofCatalysis_233_242_2005.pdf

Oxidation of CO in H2-CO mixtures catalyzed by platinum: alkali effects on rates and selectivity

Stability and distribution of cesium in Cs-promoted silver catalysts used for butadiene epoxidation

Effects of chlorine and chlorine dynamics during silver-catalyzed epoxidation of butadiene

Disclosed is a process for the efficient removal of carbon dioxide from a gas recycle system generated in an epoxidation process wherein 1,3-butadiene is selectively oxidized to 3,4-epoxy-1-butene. Carbon dioxide at low partial pressure is absorbed into an alkanolamine solution from a low pressure recycle gas stream containing high levels of oxygen. Also disclosed is a means for reclaiming the alkanolamine from a solution of a carbon dioxide-alkanolamine salt or adduct formed in the carbon dioxide removal process.

Process for the removal of carbon dioxide from 3,4-epoxy-1-butene process recycle streams

Disclosed herein is an improved gas phase process for the selective epoxidation of non-allylic olefins wherein the epoxidation is carried out in the presence of certain inert, paraffin hydrocarbons. Such hydrocarbons possess higher heat capacities as compared to other materials, e.g., nitrogen, argon, methane and helium, typically used as inert diluents in olefin epoxidations. The disclosed process is particularly useful for the continuous manufacture of 3,4-epoxy-1-butene from 1,3-butadiene.

Gas phase process for the epoxidation of non-allylic olefins

Disclosed are bis-phosphine compounds having the general formula (see fig. I) wherein: each of A1, A2, A3 and A4 is an arylene radical wherein (i) each phosphorus atom P is bonded to a ring carbon atom of A1 and A2 and to a ring carbon atom of A3 and A4, (ii) A1 and A2, and A3 and A4 are bonded to each other by ring carbon atoms and (iii) each of the residues (see fig. II) and (see fig. III) constitutes a 5-membered ring; each of A5 and A6 is an arylene radical wherein A5 and A6 are bonded to each other and to residues R1-C-R2 and R3-C-R4 by ring carbon atoms and R1-C-R2 and R3-C-R4 are connected to each other through a chain of 4 carbon atoms; and R1, R2, R3 and R4 each represents hydrogen or a hydrocarbyl radical containing up to about 8 carbon atoms. Also disclosed are catalyst systems comprising one or more of the above phosphine compounds and rhodium, catalyst solutions comprising one or more the above phosphine compounds, rhodium and a hydroformylation solvent, and hydroformylation processes wherein olefins are contacted with carbon monoxide, hydrogen and the catalyst solution to produce aldehydes.

Jerome Leonard Stavinoha

Papers

Stability and distribution of cesium in Cs-promoted silver catalysts used for butadiene epoxidation

Effects of chlorine and chlorine dynamics during silver-catalyzed epoxidation of butadiene

Process for the removal of carbon dioxide from 3,4-epoxy-1-butene process recycle streams

Gas phase process for the epoxidation of non-allylic olefins

Hydroformylation process using novel phosphine-rhodium catalyst system