Paul Schubert - Academia.edu (original) (raw)

Papers by Paul Schubert

121 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.Ultrasonic irradiation of ... more 121 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.Ultrasonic irradiation of solutions produces accoustic cavitation; the formation, growth and violent collapse of gas bubbles in solution. During collapse of the bubbles, local temperatures of approximately 3300 K and pressures of approximately 300 atm may be produced. These high temperatures and pressures may give rise to high energy species in solution. Sonications were performed using a Heat-Systems Ultrasonics model W375 Sonicator cell disruptor with a sample cell equipped for cryogenic and inert atmosphere work. Sonication of the stable free radical diphenylpicryhydrazyl in a variety of solvents resulted in bleaching of its intense color, and demonstrated the ability of a wide range of organic solvents to support sonochemical reactions. Sonication of iron pentacarbonyl, neat or in hydrocarbon solvents, produces triiron dodecacarbonyl and finely divided iron powder. The ratio of these products may be varied by changing the vapor pressure of the solvent. The mechanism for formation of triiron dodecacarbonyl is believed to be initial formation of an iron tricarbonyl species which then reacts sequentially with two iron pentacarbonyls in solution to produce the triiron compound. Sonication of iron pentacarbonyl with phosphine and phosphite ligands yields a mixture of mono- and disubstituted products, which are formed in a constant ratio with time. Sonication of iron tetracarbonyl triphenylphosphine in excess ligand does not yield further substitution products. Sonication of chromium hexacarbonyl with phosphines gives similar results. Sonication of dimanganese decacarbonyl or dirhenium decacarbonyl in halogenated solvents gives the mononuclear metal pentacarbonyl halide complex. Only dimanganese decacarbonyl undergoes sonochemical substitution with phosphines. Sonication of one atmosphere of carbon monoxide in organic solvents leads to slow production of methane and methanol. The rates are not increased by addition of metal complexes or promoters. Sonication of ruthenium and osmium dodecacarbonyls under hydrogen and carbon monoxide produces ruthenium and osmium pentacarbonyls. Sonication of dicobalt octacarbonyl gives the triply bridged methlidyne tricobalt nonacarbonyl and tetracobalt dodecacarbonyl as soluble products.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Oil & Gas Journal, Sep 12, 1988

Methods for testing Claus catalysts are developed that more accurately represent the actual opera... more Methods for testing Claus catalysts are developed that more accurately represent the actual operating conditions in commercial sulfur recovery units. For measuring catalyst activity, an aging method has been developed that results in more meaningful activity data after the catalyst has been aged, because all catalysts undergo rapid initial deactivation in commercial units. An activity test method has been developed where catalysts can be compared at less than equilibrium conversion. A test has also been developed to characterize abrasion loss of Claus catalysts, in contrast to the traditional method of determining physical properties by measuring crush strengths. Test results from a wide range of materials correlated well with actual pneumatic conveyance attrition. Substantial differences in Claus catalyst properties were observed as a result of using these tests.

Journal of the American Chemical Society, Dec 1, 1981

The chemical effects of high-intensity ultrasound have long been known to arise from cavitation: ... more The chemical effects of high-intensity ultrasound have long been known to arise from cavitation: the creation, expansion, and adiabatic compression of gas vacuoles in solution during sonication.' The intense, but transient, local heating and compression produced during cavitation have been calc~lated*~~ to reach as high as 10000 OC and 10000 atm, thus producing a variety of highenergy species in solution. The effects of high-intensity ultrasound

<jats:title>Abstract</jats:title> <jats:p>This study compared diesel exhaust em... more <jats:title>Abstract</jats:title> <jats:p>This study compared diesel exhaust emission for a low sulfur and a Fischer-Tropsch (F-T) diesel fuel. The comparison included regulated emissions, airtoxics, aldehydes/ketones, and greenhouse gas emissions. Testing was conducted using a Cummins B-Series engine installed in a heavy light-duty truck operating on a chassis dynamometer and on an engine dynamometer. The chassis driving cycles included city, highway, and aggressive driving operation. Engine dynamometer tests included the U.S. transient cycle. Results showed that the F-T diesel fuel substantially reduced emissions although the engine was not specifically tuned to take advantage of the unique characteristics of F-T diesel fuel.</jats:p>

Chemistry of Materials, Jul 1, 1989

state formalism, and these we have discussed. The bonding between tellurium and transition-metal ... more state formalism, and these we have discussed. The bonding between tellurium and transition-metal atoms is highly covalent. Weak paramagnetism might result from both itinerant and localized electrons.

Journal of the American Chemical Society, Sep 1, 1983

Irradiation of liquids with high-intensity ultrasound creates, via cavitation, localized hot spot... more Irradiation of liquids with high-intensity ultrasound creates, via cavitation, localized hot spots with transient pressures of >300 atm and temperatures-3000 K. We report the first studies of the chemical effects of ultrasound on Mn2(CO),o, MnRe(CO)lo, and Re,(CO),,. Ultrasonic irradiation of Mn2(CO)lo produces ligand substitution by phosphines or phosphites. The rate of this substitution is independent of the choice of ligand or of its concentration, and the mechanism of substitution does not involve metal-metal bond cleavages. MnRe(CO),, and Re2(CO),, do not undergo sonochemical ligand substitution at appreciable rates, presumably because their lower vapor pressures preclude their presence in the cavitation event. In addition, we have found that Mn2(CO)lo and Re2(CO)lo undergo rapid sonochemical halogenation with halocarbon solvents, with rate enhancement of los. The primary sonochemial event in these halogenations is homolysis of the solvent, generating halogen atoms (which can be trapped by M2(CO),, or by alkane solvent) and carbon radicals (which dimerize and have been so characterized). The group 7B metal carbonyls provide an ideal system for the comparison of metal-ligand to metal-metal reactivity. The recent interest in their thermal' and photochemical2 behavior has led us to initiate the investigation of the sonochemistry of Mn2(CO)lo, MnRe(CO)',, and Re2(CO)lo. Sonochemistry originates from the creation of acoustic cavitation3 by high-intensity ultrasound; this rapid formation, growth, and violent collapse of gas vacuoles in liquids generate short-lived (Cnanosec) localized hot spots whose peak temperatures and pressures have been measured at-3000 K and-300 atm: confirming earlier calculation^.^ Analogies to photochemistry, radiolysis, radio-frequency discharge, and other high-energy processes can be made. Several recent reports on the chemical effects of ultrasound in heterogeneous6 and homogeneous' systems may be noted.

Chemischer Informationsdienst, Dec 6, 1983

ChemInform Abstract Ultraschallbestrahlung von Flüssigkeiten verursacht akustische Hohlraumbildun... more ChemInform Abstract Ultraschallbestrahlung von Flüssigkeiten verursacht akustische Hohlraumbildung und damit zusammenhängend das Auftreten von sogenannten "heissen Flecken" mit Spitzentemp. von ca. 3000 K und einer Lebensdauer von einer Nanosekunde. Die Behandlung mit Ultraschall hoher Intensität bewirkt bei verschiedenen Metallcarbonylen eine sonochemische Liganddissoziation, dieüber intermediär auftretende koordinativ ungesättigte Spezies zu mehrfacher CO-Substitution führt. Fe(CO)5 liefert z.B. bei Sonolyse ohne Zugabe zusätzlicher Liganden Fe3(CO)12 und in Gegenwart anderer Liganden wie Phosphine oder Phosphite die Verbindungen Fe(CO)3L2 und Fe(CO)4L.Ähnliche Substitutionen werden für Fe3(CO)12, Mn2(CO)10, Cr(CO)6, Mo(CO)6 und W(CO)6 beobachtet. Die Kinetik dieser Reaktionen und ihr Mechanismus werden untersucht. Weiterhin kann die durch Ultraschall initiierte Liganddissoziation als neue Methode der Katalysatoraktivierung für die Alken-Isomerisierung eingesetzt werden. Trotz der bestehendenÄhnlichkeiten zwischen Sonokatalyse und Photokatalyse wurden unterschiedliche relative Wirksamkeiten und Selektivitäten beobachtet.

American Chemical Society eBooks, Feb 23, 1994

American Chemical Society eBooks, Sep 12, 1988

Chemischer Informationsdienst, Mar 16, 1982

Studies in Surface Science and Catalysis, 2001

ChemInform, Aug 19, 2010

Waste HBr is formed during the bromination of many organic molecules, such as flame retardants, p... more Waste HBr is formed during the bromination of many organic molecules, such as flame retardants, pharmaceuticals, and agricultural chemicals. For over 50 years attempts to recover the bromine from waste HBr by catalytic oxidation have been unsuccessful due to low catalyst activity and stability. The discovery of a new high-activity catalysts with excellent long-term stability and life capable of high HBr conversion below 300{degrees}C has made catalytic oxidation of waste HBr commercially feasible. The oxidation of anhydrous HBr using oxygen is highly exothermic, giving an adiabatic temperature rise of 2000{degrees}C. Use of 48 wt% HBr in the oxidation reduces the adiabatic temperature rise to only 300{degrees}C. A multitubular heat exchanger type of reactor can then be used to manage the heat. A 5,000 kg/yr pilot plant was built to verify the performance of the catalyst, the suitability of the reactor materials of construction, and the multibular reactor concept. The pilot unit has a single full-scale reactor tube 4 m long and 2.54 cm in diameter with a hot oil jacket for heat management. Excellent catalyst stability was observed during a 600 h catalyst-life test. HBr conversion of 99% was maintained throughout the run, and over 360 kg of bromine wasmore » produced. The temperature at a localized hot spot near the reactor inlet was only 15-20{degrees}C above the reactor inlet temperature, indicating efficient heat management.« less

SAE Technical Paper Series, Sep 24, 2001

... The comparison included regulated emissions, hydrocarbon speciation, air toxics, aldehydes an... more ... The comparison included regulated emissions, hydrocarbon speciation, air toxics, aldehydes and ketones ... fuel, and these fuels substantially reduced emissions although the engine was not ... appropriate SAE Member discount will be applied through the Shopping Cart process. ...

Applied Catalysis, 1988

Poisoning of fluid cracking catalysts by vanadium, nickel, iron and copper can decrease the seIec... more Poisoning of fluid cracking catalysts by vanadium, nickel, iron and copper can decrease the seIectivity and overall activity of such catalysts. Silica alumina is often used as a matrix to disperse the active zeolite component, to crack large hydrocarbons at initial stages of reaction and for stability of the fluid cracking catalyst. Vanadium poisons are particularly bothersome due to zeolite destruction by vanadium. This paper explores the interaction of vanadium with various silica aluminas including those with rare earth and magnesia contents. The effects of calcination and steaming were also determined. Spectroscopic techniques such as luminescence, diffuse reflectance, electron paramagnetic resonance, X-ray photoelectron spectroscopy and secondary ion mass spectrometry methods were used to study the oxidation state, chemical composition, and number and type of vanadium species in these materials. The results show that vanadium moves into the particle interior when magnesium or rare earth oxides are present. This is responsible for the decreased mobility of vanadium even during steaming conditions and results in higher catalytic selectivity for catalysts containing these materials.

Journal of the American Chemical Society, Sep 1, 1983

calculated using statistical thermodynamics matched the measured aS from equilibrium studies.39 F... more calculated using statistical thermodynamics matched the measured aS from equilibrium studies.39 Finally the zero-point energy differences between H20.H30+ and H 3 0 + + H 2 0 was calculated using statistical thermodynamics from known heats of formation,@ the proton affinity of H20,41 and the A H of reaction A-1 from equilibrium studies.39 Parameters for the CO, system were evaluated in a similar way to those for the water system. Vibrational frequencies and rotational constants of C02+. and CO, are available from spectroscopic studies.42 Since we could find no experimental or theoretical information on the structure of CO2.CO2+., we assumed that the CO, moieties are parallel with a CC distance of 2 A to calculate the rotational constant. The vibrational frequencies of C0,-CO2+. and the zero-point energy difference were evaluated as described above for H20.H30+ using the AS and AH recently measured by Headley et aL5 For H20.H30+ and C02.C02+-there are several reported measurements of AH and A S. 5 8 3 9 3 4 3 v 4 4 The AH values agree within (39) A

The overall objective of this project (Phases I through III) is to develop a sensor array based i... more The overall objective of this project (Phases I through III) is to develop a sensor array based instrument that provides simple, reliable and economical stack gas measurement of oxygen, carbon monoxide and oxides of nitrogen from natural gas-fired processes. The report summarizes the development of the sensor array and the integration of the array into an advanced prototype continuous emissions monitor (CEM).

Preprints-American Chemical Society Division of Petroleum Chemistry, Aug 1, 1987

The effect of Ni and V on FCC catalysts has long been known. Nickel has generally been found to m... more The effect of Ni and V on FCC catalysts has long been known. Nickel has generally been found to make 2-5 times more coke and hydrogen than V, with the relative effect of Ni decreasing as the level of contaminant metals increases. Vanadium not only produces coke and hydrogen like Ni, but also deactivates the catalyst. The recent development of extremely high activity (high zeolite level) cracking components allows examination of contaminant metals effects on both zeolitic and non-zeolitic particles at reasonable cat-to-oil and conversion levels. This provides insights to the activity and selectivity of the metals present of different catalyst structures and chemical compositions in both multicomponent systems (containing both zeolitic and non-zeolitic particles) and integrated zeolite-matrix particles.

Chemistry of Materials, Jul 1, 1992

Industrial chemistry library, 1995

Publisher Summary Recycle of HBr to bromine is highly desirable both from an economic and an envi... more Publisher Summary Recycle of HBr to bromine is highly desirable both from an economic and an environmental standpoint. Catalytic oxidation offers the potential to recycle HBr from contaminated waste streams to bromine. This chapter illustrates that the oxidation catalyst is stable against deactivation by a wide range of contaminants found in waste HBr streams. Strategies to deal with the contaminants will depend on the recycle applications in which the catalytic oxidation unit serves. In the case of HCl-contaminated feeds, it is expected that the most economical operating mode will achieve less than complete HBr conversion. This will yield bromine that is essentially free of chlorine contamination and eliminate the need to purify the bromine by distillation. The process effluent stream will then be a mixed HCI-HBr stream, where the ratio of the two acids depends on the starting HC1 concentration and the actual conversion level chosen. The feasibility of using, selling, or disposing of this stream is site specific.

Journal of engineering for gas turbines and power, Apr 1, 1998

Continuous emissions monitoring of gas turbine engines in pipeline service have typically been mo... more Continuous emissions monitoring of gas turbine engines in pipeline service have typically been monitored using either laboratory derived instruments (CEMS), or predicted using data from low cost sensors on the engines and algorithms generated by mapping engine performance (PEMS). A new cost-effective system developed under a program sponsored by the Gas Research Institute (Chicago) combines the advantages of both systems to monitor engine emissions in gas transmission service. This hybrid system is a sensor-based analyzer that uses a sensor array, including a newly developed NOx sensor, to directly monitor NOx, CO, and O2 emissions at the stack. The gases are measured hot and wet, The new systems were installed and tested on a gas-fired Rolls Royce Spey turbine engine and on Ingersoll-Rand KVG-410 and Cooper GMVH-10 reciprocating engines in gas transmission service. These systems passed the Relative Accuracy Test (Part B) required under U.S. EPA regulations (40 CFR 60).

Oil & Gas Journal, Sep 12, 1988

Journal of the American Chemical Society, Dec 1, 1981

Chemistry of Materials, Jul 1, 1989

Journal of the American Chemical Society, Sep 1, 1983

Chemischer Informationsdienst, Dec 6, 1983

American Chemical Society eBooks, Feb 23, 1994

American Chemical Society eBooks, Sep 12, 1988

Chemischer Informationsdienst, Mar 16, 1982

Studies in Surface Science and Catalysis, 2001

ChemInform, Aug 19, 2010

SAE Technical Paper Series, Sep 24, 2001

Applied Catalysis, 1988

Journal of the American Chemical Society, Sep 1, 1983

Preprints-American Chemical Society Division of Petroleum Chemistry, Aug 1, 1987

Chemistry of Materials, Jul 1, 1992

Industrial chemistry library, 1995

Journal of engineering for gas turbines and power, Apr 1, 1998