摘要:

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].

ISSN:0161-4940    

DOI:10.1080/01614948408064725

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

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].

ISSN:0161-4940    

DOI:10.1080/01614948408064726

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

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.

ISSN:0161-4940    

DOI:10.1080/01614948408064727

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

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 TiC13have 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.

ISSN:0161-4940    

DOI:10.1080/01614948408064728

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

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.

ISSN:0161-4940    

DOI:10.1080/01614948408064729

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

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.

ISSN:0161-4940    

DOI:10.1080/01614948408064730

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

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.

ISSN:0161-4940    

DOI:10.1080/01614948408064731

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

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.

ISSN:0161-4940    

DOI:10.1080/01614948408064732

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0161-4940    

DOI:10.1080/01614948408064714

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor