Irving Wender

Reactions of synthesis gas

Abstract The use of synthesis gas (syngas) offers the opportunity to furnish a broad range of environmentally clean fuels and chemicals. There has been steady growth in the traditional uses of syngas. Almost all hydrogen gas is manufactured from syngas and there has been a tremendous spurt in the demand for this basic chemical; indeed, the chief use of syngas is in the manufacture of hydrogen for a growing number of purposes. Methanol not only remains the second largest consumer of syngas but has shown remarkable growth as part of the methyl ethers used as octane enhancers in automotive fuels. The Fischer-Tropsch synthesis remains the third largest consumer of syngas, mostly for transportation fuels but also as a growing feedstock source for the manufacture of chemicals, including polymers. Future growth in Fischer-Tropsch synthesis may take place outside the continental United States. The hydroformylation of olefins (the oxo reaction), a completely chemical use of syngas, is the fourth largest use of carbon monoxide and hydrogen mixtures; research and industrial application in this field continue to grow steadily. A direct application of syngas as fuel (and eventually also for chemicals) that promises to increase is its use for Integrated Gasification Combined Cycle (IGCC) units for the generation of electricity (and also chemicals) from coal, petroleum coke or heavy residuals. In the period 2005–2015, the amount of syngas employed in this manner may approach that used for all other specific purposes. Syngas is the principal source of carbon monoxide, which is used in an expanding list of so-called carbonylation reactions.

The effect of alkali promotion on CO hydrogenation over Rh/TiO2

To develop a better understanding of the link between alkali promotion of hydrocarbon synthesis and that of oxygenate synthesis, CO hydrogenation over both unpromoted and promoted RhTiO2 was studied in a differential reactor at 250–300 °C, 1–10 atm, and COH2 = 2. The ability of the alkali species to promote the selectivity for oxygenated compounds increased in the order unpromoted Li > K > Cs. The promoters also showed a strong hydrogenation-suppression ability which may have caused the decrease in hydrocarbon selectivity and activity. The activities and selectivities of RhTiO2 and alkali-promoted RhTiO2 appear to be correlated with their catalytic abilities for hydrogenation, CO dissociation, and CO insertion. Results for unpromoted RhSiO2 are also presented for Comparison purposes.

Extraction of coal using supercritical water

Abstract An experimental apparatus was developed to inject coal into an autoclave containing preheated supercritical water. The supercritical water appears to act as both solvent and reactant in the conversion of coal to gases and liquids. Experiments were carried out with German brown coal, lignite and bituminous coal and with glucose at both subcritical and supercritical water densities. A significantly larger quantity of char was obtained when operating at subcritical densities and when the coal was mixed with water before heating to supercritical conditions. Smaller amounts of char were obtained as density increased and as reaction time increased.

The use of probe molecules in the study of CO hydrogenation over SiO2-supported Ni, Ru, Rh, and Pd

Abstract CO hydrogenation over Ni SiO 2 , Ru SiO 2 , Rh SiO 2 and Pd SiO 2 was studied by the addition of various probe molecules (C 2 H 4 , CH 3 CH 2 OH, and CH 3 CHO) to the reactant stream under synthesis conditions. The well-known differences among these catalysts in product formation (methane, higher hydrocarbons, C 2+ oxygenates and methanol) were shown to be due to differences in their activities to catalyze hydrogenation, hydrogenolysis, dehydrogenation, decarbonylation, CH x insertion, and CO insertion rather than just CO dissociation. Ni SiO 2 and Pd SiO 2 exhibited weak activities for the incorporation of these probe molecules into higher hydrocarbons and oxygenates. Rh SiO 2 , a good catalyst for the production of C 2 oxygenated compounds, showed strong activity for CO insertion and for the incorporation of ethylene and ethanol into C 3+ oxygenated compounds. Ru, a higher hydrocarbon synthesis catalyst, displayed fairly strong activities for the incorporation of ethanol and acetaldehyde into C 3+ hydrocarbons. Probing of the surface under reaction conditions by the addition of certain reacting molecules provides an excellent method for developing a better understanding of reaction mechanisms as well as of fundamental properties of catalysts under those conditions.

Slurry phase synthesis of methanol with a potassium methoxide/copper chromite catalytic system

Abstract The use of methanol as a fuel additive and in methyl t-butyl ether (MTBE) production has renewed interest in the search for improved methanol processes. A slurry phase concurrent synthesis of methanol using a potassium methoxide/copper chromite mixed catalyst which operates under relatively mild conditions (100–180°C, 30–65 atm) is described. The reaction pathway likely involves a homogeneous carbonylation of methanol to methyl formate followed by the heterogeneous hydrogenolysis of methyl formate to two molecules of methanol - the net result being the reaction of hydrogen with carbon monoxide to give methanol via methyl formate. The copper chromite also catalyzes the regeneration of the potassium methoxide catalyst in solution from potassium formate and potassium methyl carbonate resulting in tolerance to small amounts of water and carbon dioxide. A synergistic effect between the potassium methoxide and copper chromite results in high rates of methanol formation in the concurrent synthesis.

Hybrid zirconia catalysts for conversion of Fischer–Tropsch waxy products to transportation fuels

Conversion of long-chain normal paraffins found in Fischer–Tropsch products to high-quality transportation fuels, especially middle range products, was investigated using model hydrocarbons (n-C24 and n-C36) and a Fischer–Tropsch wax over modified zirconia catalysts. Most work was carried out using n-C24 as a representative reactant. With Pt-promoted tungstated zirconia (Pt/WO3/ZrO2, 0.5 wt.% Pt and 12.5 wt.% W) used as a base, addition of sulfated zirconia (SO4/ZrO2), tungstated zirconia (WO3/ZrO2) or certain zeolites increased its reactivity and selectivity at 200 °C to middle range products such as kerosene and diesel fuel. The effect of improving the performance of Pt/WO3/ZrO2 by adding the zeolite, mordenite, was studied in detail; an optimal mixing ratio exists for maximum conversion of n-C24 under certain reaction conditions. The hybrid catalysts are physical mixtures of compounds with different functions. Hybrid catalysts based on Pt/WO3/ZrO2 provide a promising way to obtain higher catalytic activity and higher selectivity for desired transportation fuels from Fischer–Tropsch products.

Kinetics of two-step methanol synthesis in the slurry phase

Abstract The carbonylation of methanol using potassium methoxide catalyst and hydrogenolysis of methyl formate using a copper-chromite catalyst (39% Cu; 37% Cr and 3% Mn) were studied in the temperature ranges of 60–110°C and 100–140°C and pressure ranges of 25–65 and 30–60 bar respectively in a mechanically agitated reactor. Kinetic rate expressions are presented for both reactions. The carbonylation reaction was found to be rapid and limited by equilibrium at the conditions studied. The apparent activation energy for the carbonylation was found to be 67.7 ± 1.5 kJ/mol. CO 2 reacts with the potassium methoxide catalyst and stops the reaction. The hydrogenolysis reaction was found to be slow at the studied conditions with an apparent activation energy of 69.8 ± 2.0 kJ/mol. CO inhibited the hydrogenolysis reaction over the copper-chromite catalyst used. CO 2 poisoned the copper-chromite catalyst. A Langmuir-Hinshelwood type rate model was used to fit the experimental data. A brief discussion of the feasibility of the two-step methanol synthesis in a single stage reactor is given. The data would be useful for evaluating the possibility of synthesizing methanol from H 2 and CO using these reactions either in two separate reactors or concurrently in one reactor.

Anion-modified zirconia: effect of metal promotion and hydrogen reduction on hydroisomerization of n-hexadecane and Fischer–Tropsch waxes

Abstract The effect of metal promoters on the activity and selectivity of tungstated zirconia (8 wt.% W) for n -hexadecane isomerization in a trickle bed continuous reactor is studied by using different metals (Pt, Ni, and Pd) and, in one case, by varying metal loading. Platinum is found to be the best promoter. The effect of hydrogen reduction is investigated using platinum-promoted tungstated zirconia catalysts (Pt/WO 3 /ZrO 2 , 0.5 wt.% Pt and 6.5 wt.% W). Pretreatment at temperatures between 300 and 400°C for 3 h in hydrogen is found to be slightly beneficial for achieving high yields of isohexadecane. A platinum promoted sulfated zirconia (Pt/SO 4 /ZrO 2 ) is compared with a Pt/WO 3 /ZrO 2 catalyst for the hydroisomerization of n -hexadecane in the same reactor at the same n -hexadecane conversion. The former is a good cracking catalyst and the latter is suitable for use as a hydroisomerization catalyst. In a 27-ml microautoclave reactor, studies of the hydroisomerization and hydrocracking of two Fischer–Tropsch (F–T) wax samples are carried out. Severe cracking can be effectively suppressed using a Pt/WO 3 /ZrO 2 catalyst so as to obtain branched isomers in the diesel fuel or lube-base oil range.

Chemicals from Methanol

Abstract For good reasons, there has been a spate of articles, much thinking, and a fair amount of industrial action on making chemicals and fuels from methanol, Only methane and methanol are made commercially in over 99% yields from synthesis gas.

Methanol synthesis via methylformate in a slurry reactor

Abstract The synthesis of methanol from CO and H 2 using a reaction sequence in which methanol is first carbonylated to methylformate and then hydrogenated to methanol was studied. The reaction occurred concurrently in a single mechanically agitated slurry reactor using the usual homogeneous formate synthesis catalyst (CH 3 OK) and a heterogeneous catalyst (copper-chromite) at temperatures of 140 to 180°C and pressures of 38 to 62 bar. The concurrent operation is not a simple summation of the two individual reactions. It is likely that the CH 3 OK is adsorbed on the copper-chromite. The rate of formation of methanol is significantly higher than predicted from the individual reactions and the deleterious effect of CO 2 on the CH 3 OK catalyzed carbonylation of methanol and on the hydrogenolysis of methyl formate is reversible. The carbonylation reaction is in equilibrium under the conditions studied. A progressive reduction in reaction rate with time was found and is attributed to the effect of CO on the hydrogenolysis catalyst. Comparisons are made of the concurrent methanol synthesis in a slurry reactor with alternative methods of methanol synthesis.