Showing papers in "Catalysis Reviews-science and Engineering in 1984"
TL;DR: A large amount of work has been devoted to the understanding of the structural and chemical form in which the different elements are present in the active catalyst and the establishment of correlations between such information and the various catalytic functions.
Abstract: The great current interest in hydrodesulfurization (HDS) and other hydrotreating reactions is related to the need for efficient upgrading of crude oil fractions or coal-derived liquids. The catalysts used for such reactions generally consist of molybdenum (or tungsten) supported on high surface area aluminas with cobalt or nickel added as promoters. Great efforts have been devoted to the understanding of the structural and chemical form in which the different elements are present in the active catalyst and to the establishment of correlations between such information and the various catalytic functions. This massive research effort has given valuable information on many aspects of such catalyst systems (for recent reviews of the extensive literature, see, e.g., Refs. 1–11). However, it has not been possible to reach general agreement on the types of structures present in the active catalysts and the origin of promotion
428 citations
TL;DR: In this paper, it was found that Co, Ni, Mo, and W catalysts were the most active and least expensive of the transition metal sulfides and their mixtures.
Abstract: Hydroprocessing catalysts based upon the transition metal sulfides have been widely used for over 60 years and catalysts such as Co/Mo/Al2O3 remain the industry “workhorses” in hydroprocessing of petroleum-based feedstocks [1]. Such applications include sulfur removal (hydrodesulfurization), nitrogen removal (hydrogenitrogenation), and product quality improvement (hydrotreating, hydroconversion). Original interest (prior to World War II) in these catalysts centered on their activityin the hydrogenation of coal liquids which contain considerable amounts of sulfur, thus maintaining the transition metal in the sulfided state. It was quickly discovered that Co, Ni, Mo, and W sulfides and their mixtures were the most active and least expensive of the transition metal sulfides [2]. Later (post-World War II) their major uses shifted to hydroprocessing of sulfur- and nitrogen-containing petroleum-based feedstocks with Co- and Ni-promoted Mo and W catalysts usually supported on Al2O3. However, as petroleu...
314 citations
TL;DR: Light olefins will play a dominant role in any future methanol-based chemicals economy as discussed by the authors, and they are initial products in the conversion of methanoline to hydrocarbons over zeolite catalysts.
Abstract: Light olefins will play a dominant role in any future methanol-based chemicals economy. Olefins are initial products in the conversion of methanol to hydrocarbons over zeolite catalysts [1]. The overall reaction path may be represented by
247 citations
TL;DR: In this article, the authors present an overview of the available information on the mechanism of catalytic catalytic gasification catalyst action, and discuss the need to collate, summarize, and interpret this information.
Abstract: Recently, interest in catalytic gasification of carbon has expanded rapidly. In consequence of the volume and diversity of this interest, there is a need to collate, summarize, and interpret the available information on the mechanism of gasification catalyst action.
210 citations
TL;DR: In this paper, a planar transition aluminas is used as a model for alumina-based catalysts, which are used commercially for adsorbents, catalysts and catalyst supports.
Abstract: Planar transition aluminas are gaining attention as models for alumina-based catalysts [I] because of their attractiveness for study by modern surface analytical techniques [2], electron optical methods [3], and reflection spectroscopy [4–7]. In this context “planar” means a thin (<10–4 cm) flat oxide layer of uniform thickness. Conventional high surface area aluminas which are used commercially for adsorbents, catalysts, and catalyst supports usually require grinding and /or pressing into disks for characterization by these approaches. This can expose unwanted inner structures or expose the samples to potential contamination by the grinding and pressing tools or uncontrolled atmospheres. In addition, difficulties arise in attempting to study the various stages of alumina development involved with commercial methods since these entail sols, gels, powdered hydroxides, and other inconvenient structures.
143 citations
TL;DR: In this paper, the authors used extended x-ray absorption fine structure (EXAFS) as a probe for the study of catalysts and demonstrated the utility of EXAFS for very highly dispersed catalysts.
Abstract: In recent years the utility of extended x-ray absorption fine structure (EXAFS) as a probe for the study of catalysts has been clearly demonstrated [1–13]. Measurements of EXAFS are particularly valuable for very highly dispersed catalysts. Supported metal systems, in which small metal clusters or crystallites are commonly dispersed on a refractory oxide such as alumina or silica, are good examples of such catalysts. The ratio of surface atoms to total atoms in the metal clusters is generally high and may even approach unity in some cases. With such catalysts it is difficult or impossible to obtain structural information by conventional x-ray diffraction methods [14].
106 citations
TL;DR: A voluminous patent and scientific literature describing transition metal catalysts for olefin polymerization has emerged since the original discoveries by Ziegler, Natta, and other workers as mentioned in this paper.
Abstract: Catalysis continues to play a vital role in polymerization of such olefins as ethylene and propylene. A voluminous patent and scientific literature describing transition metal catalysts for olefin polymerization has emerged since the original discoveries by Ziegler, Natta, and other workers [1–6], Significant progress in polymerization catalysis has been made in the last 15 years, particularly with the development of methods to increase the efficiency of transition metal catalysts in olefin polymerization. Success in this area has provided the basis of simplified, less costly plant operations which do not require removal of residual catalyst from the polymer [3–9].
80 citations
TL;DR: Fluid catalytic cracking of petroleum to produce gasoline began in about 1912 as mentioned in this paper, and the early pioneering work was carried out by Eugene Houdry [1] and was developed at Exxon and commercially developed in about 1940 using amorphous catalysts.
Abstract: Catalytic cracking of petroleum to produce gasoline began in about 1912. The early pioneering work was carried out by Eugene Houdry [1]. Modern fluid catalytic cracking (FCC) was conceived at Exxon and commercially developed in about 1940 [2] using amorphous catalysts. Fluid catalysts are small spherical particles ranging from 40 to 150 um in diameter with acid sites capable of cracking large petroleum molecules to products boiling in the gasoline range. One advantage of the FCC process is the absence of the diffusion limitations present in conventional gas oil cracking due to the small size of the catalyst particle. Since 1964 virtually all catalysts contain faujasite, a stable, large pore, Y-type zeolite dispersed in a silica/alumina matrix [3]. The catalytic aspects of contemporary FCC processes have been reviewed by Venuto and Habib [4], Gates, Katzer, and Schuit [5], Magee and Blazek [6], and Magee [7]. A more recent update of refinery trends has been made available by Blazek [8].
63 citations
TL;DR: In this article, the authors described the preparation of a member of a generation of new synthetic zeolites, called ZSM-5, which was unique because of its high silica/alumina ratio and greatly reduced coking rates for reactions with hydrocarbons.
Abstract: It has been about 20 years since Plank, Rosinski, and Hawthorne reported their spectacular results with metal-modified zeolite cracking catalysts for more efficient production of gasoline [1]. This discovery has saved an estimated 200 million barrels of crude oil each year in the United States alone [2]. In 1972, a patent by Argauer and Landolt described the preparation of a member of a generation of new synthetic zeolites, called ZSM- 5. It was unique because of its high silica/alumina ratio and greatly reduced coking rates for reactions with hydrocarbons by comparison with known low silica zeolites [3]. This material was an early member of a series of over 50 synthetic zeolitic substances prepared in Mobil laboratories.
59 citations
TL;DR: 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 methanoline are made commercially in over 99% yields from synthesis gas as discussed by the authors.
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.
48 citations
TL;DR: The United States used to import 46% of its oil and petroleum products from Saudi Arabia, Iran, and other OPEC nations, but by September 1, 1983, the United States imported only 28% of their oil.
Abstract: Many industrialized western countries depend on imported foreign crude. In 1977, for example, the United States imported 46% of its oil and petroleum products, chiefly from Saudi Arabia, Iran, and other OPEC nations. By September 1, 1983, the United States imported only 28% of its oil. The chief suppliers were Mexico, with 826,000 barrels per day, Canada, with 479,000, and Venezuela, with 419,000. Saudi Arabia is now seventh on the list of suppliers for the United States. This shift is responsible for the trend toward a heavier crude supply mix on the international market. Transportation fuels and petrochemical feedstocks are in increasing demand; hence many refiners would like to get out of the fuel oil business, More “bottom-of-the-barrel” conversion capability will be required in many refineries to efficiently process these heavier feedstocks and maximize production of light products.
TL;DR: In the past decade remarkable progress has been made in the surface science of catalysis as discussed by the authors, and it seems clear that concepts gleaned from studies on single crystal surfaces will strongly influence the research with supported metal catalysts and ultimately affect the nature of the materials used as practical catalysts.
Abstract: In the past decade remarkable progress has been made in the surface science of catalysis. Studies on both small single crystal metal particles on supporting materials and on large (bulk) single crystals point toward a more refined understanding of the fundamental processes underlying catalytic chemistry and, hopefully, toward a rational design of catalytic materials. It seems clear that concepts gleaned from studies on single crystal surfaces will strongly influence the research with supported metal catalysts and ultimately affect the nature of the materials used as practical catalysts.
TL;DR: In the past 35 years, the chemical industry has largely changed its raw material base from coal to petroleum and natural gas as discussed by the authors, which has involved a vast expenditure of money, time, and effort, but the financial incentives have been huge and a great deal of new chemistry has been uncovered.
Abstract: Over the past 35 years, the chemical industry has largely changed its raw material base from coal to petroleum and natural gas. This has basically meant a shift from acetylene chemistry and coal tar chemistry to olefin chemistry (ethylene, propylene, isobutylene and butadiene) and petroleum-derived benzene, toluene, and xylenes. Methanol, ammonia, and hydrogen are still made from synthesis gas. However, synthesis gas is now made by methane reforming instead of coal gasification. These conversions have involved a vast expenditure of money, time, and effort, but the financial incentives have been huge and a great deal of new chemistry has been uncovered.
TL;DR: Karol and Hsieh as mentioned in this paper showed that if a suitable support is found and Ti atoms can be anchored to its surface with stereoelectronic characteristics resembling those in the AA-TiCl3, then a high activity catalyst would result.
Abstract: Soon after the commercialization of the Ziegler-Natta catalyst for polyolefin production, efforts were begun to improve the productivity of the catalyst. It was realized that the α- and σ-forms of TiC13 have layered crystal structures having only chlorine atoms in the basal planes, Exposed and coordinatively unsaturated Ti sites are only found along c-axis edges of the crystallites. Therefore, if a suitable support is found and Ti atoms can be anchored to its surface with stereoelectronic characteristics resembling those in the AA-TiCl3, then a high activity catalyst would result. This search progressed from metal oxides to metal hydroxides, to metal hydroxychlorides, and finally to metal chlorides, in particular magnesium chloride. The historical developments have been discussed in detail by Karol and Hsieh at this conference.
TL;DR: Sunlight is directly converted to chemical energy in hydrogen-evolving photoelectrochemical cells with semiconductor electrodes, and their Gibbs free energy efficiency exceeds the solar-to-fuel conversion efficiency of green plants and approaches the solar -to-electrical Conversion efficiency of the best p-n junction cells.
Abstract: Optimal conversion of sunlight by a single-threshold converter, whether semiconductor-based or molecular, requires an energy gap near 1.4 eV [1–3], Tandem systems based on two semiconductors or on two light-harvesting molecules require materials with gaps near 1.8 and 1.0 eV [4]. At normal solar irradiance and at 27%, the thermodynamic limit to the solar conversion efficiency is 27% for a single converter and 36% for tandem cells [4]. For nonconcentrated sunlight the actual efficiency that has been attained is 21.9% [5]. Although the thermodynamic efficiency limits for semiconductor and molecular systems are the same, all efficient systems today are semiconductor-based.
TL;DR: In this article, the authors considered the catalytic potential of molecules in excited electronic, vibrational, or rotational states and surfaces and proved that the molecules maintained an equilibrium energy distribution throughout the reaction.
Abstract: Chemical interactions between molecules in excited electronic, vibrational, or rotational states and surfaces is a new field of catalytic science. Until recently, catalysis of chemical reactions has only been considered for molecules in their thermodynamic ground states. Most of the surface reactions to be catalyzed were exothermic or thermodynamically downhill. In carrying out endothermic reactions, the only source of energy considered has been the addition of heat. This also assured that the molecules maintained an equilibrium energy distribution throughout the reaction.
TL;DR: In this paper, the authors tried to correlate the bulk and surface properties to the preparation method for a fixed composition, and the resulting performance observed, and found that the correlation was limited.
Abstract: There have been many studies in the last 30 years on hydrotreating catalysts. The early studies involve various metals and supports and their influence on activity. Later studies have applied bulk and surface analytical techniques to defining the structure of catalysts and to activity [1–4]. Few of the papers try to correlate the bulk and surface properties to the preparation method for a fixed composition, and the resulting performance observed [5].
TL;DR: The first commercial production of indigo dye was carried out by the Badische Anilin and Soda Fabrik in Germany as discussed by the authors, who used oxidizedaniline sulfate with k2Cr2O7 and obtained the dye aniline purple or mauve.
Abstract: Great Britaiin dominated the chemical industry, particularly the dyestuff industyr, during the last half of the nineteenth century. William Henry Perkin, who had a post at the Royal College of Chemistry in London when he was 17, but who was working at the time in his home laboratory, oxidizedaniline sulfate with k2Cr2O7 and obtained the dye aniline purple or mauve. Recognizing its potential, he resigned his academic position and together with his father began commercial manufacture of the dye when he was 19 years old. Perkin retired in 1874 at the age of 36to devote ful time to research. The other important dye stuff at the time was indigo. Under Imperial Britain, India in 1890 produced 5 million pounds of indigo from the woad plant; its selling price was $3/lb. Chemists at Badische Anilin and Soda Fabrik had been trying to synthesize indigo for many years and in 1897, after 18 years of research, the company achieved the first commercial synthesis. The major stumbling block in the process had bee...
TL;DR: The use of LGO as a fuel oil for diesel engines plugs the filter and produces sulfur and nitrogen emissions as mentioned in this paper, which are aromatic type molecules which are difficult to hydrogenate.
Abstract: Since worldwide conversion processes are used to upgrade heavy oil to distillates, the hydrotreatment of light gas oil (LGO) as a downstream process has been used more extensively. This fraction (LGO) is produced from thermal or catalytic cracking or hydrocracking processes. It contains high amounts of unsaturates, nitrogen, and sulfur compounds which cause instability while in storage due to gum formation. The use of LGO as a fuel oil for diesel engines plugs the filter and produces sulfur and nitrogen emissions. These sulfur and nitrogen compounds arise from the cracking of heavy cuts and are aromatic-type molecules which are difficult to hydrogenate. This cut also possesses a low cetane index (CI) which must be increased (by aromatic hydrogenation) because of its poor motor performance. Color and color stability are associated with a high bromine number (BN, unsaturated content), nitrogen, and aromatic content. In order to improve these properties, a deep hydrogenation is sometimes required.
TL;DR: The catalytic control of automobile exhaust pollutants (hydrocarbons, carbon monoxide, nitrogen oxides) is now a common practice in the United States and Japan, and there are strong indications that the technology may be introduced in other parts of the world in the coming years as discussed by the authors.
Abstract: The catalytic control of automobile exhaust pollutants (hydrocarbons, carbon monoxide, nitrogen oxides) is now a common practice in the United States and Japan, and there are strong indications that the technology may be introduced in other parts of the world in the coming years. The simultaneous conversion of all three of the above pollutants is achieved by the near-stoichiometric operation of noble metal catalysts which are supported either on alumina particles or on alumina-washcoated cordierite monoliths, A summary of the developments which lead to this technology can be found, e. g., in Hegedus and Gumbleton [1] and references therein.
TL;DR: In contrast to the high pressure process which produced highly branched polymers with densities of 0.910 to 0.930 g/cm3, the new resins were linear and had densities between 0.940 and 0.970 as discussed by the authors.
Abstract: In the mid-1950s a series of patents on a new ethylene polymer was issued. These patents were all similar in that solid catalysts were used to produce polyethylene at relatively low ethylene pressures (Table 1). In contrast to the high pressure process which produced highly branched polymers with densities of 0.910 to 0.930 g/cm3, the new resins were linear and had densities of 0.940 to 0.970. Thus, the material made by the early ICI process became known as high pressure or low density (LDPE) polyethylene, and the new materials were called low pressure or high density (HDPE) polyethylene. This early technology for HDPE may be broadly grouped in terms of three different processes: Phillips, Standard Oil of Indiana, and Ziegler.
TL;DR: The passage of paraffins and olefins with six or more carbon atoms over catalytic metals and metal oxides can lead to ring closure, which was noticed first by three independent groups of Russian workers.
Abstract: The passage of paraffins and olefins with six or more carbon atoms over catalytic metals and metal oxides can lead to ring closure, Although this reaction was noticed first by three independent groups of Russian workers [1–3], it gained industrial importance through the work of Grosse and co-workers [4] in making toluene from heptane over alumina-supported metal oxide catalysts.
TL;DR: An overview of the history and development of molecular sieve materials since their discovery and commercialization is presented in this article, where evolutionary changes in their composition, sorptive and catalytic properties, surface selectivity, and stability characteristics are emphasized.
Abstract: An overview of the history and development of molecular sieve materials since their discovery and commercialization is presented. The evolutionary changes in their composition, sorptive and catalytic properties, surface selectivity, and stability characteristics are emphasized.
TL;DR: The recent revival of interest in the direct use of solar energy, which followed the 1973 oil crisis, has brought increased research and development activity in a number of areas such as photocatalysis, photoelectrochemical cells, and photovoltaic devices.
Abstract: The recent revival of interest in the direct use of solar energy, which followed the 1973 oil crisis, has brought increased research and development activity in a number of areas. Some of these areas are discussed here, namely photocatalysis, photoelectrochemical cells, and photovoltaic devices. At the present time there is continuing research activity in photocatalysis for various purposes, including solar energy conversion, and there is also continuing research activity in photoelectrochemical methods. However, at the present time, photovoltaic devices are the only ones in limited terrestrial application for direct solar energy conversion into electricity.