Pyrolysis synthesis

Figure 1. TEM microphoto of pyrolysis synthesis products obtained with Fe-MgO catalyst.

Taniguchi, I., and Bakenov, Z. 2005. Spray pyrolysis synthesis of nanostructured LiFe, Mn2/),i cathode materials for lithium-ion batteries. Powder Technology 159, 55-62. 

Nyman M, Caruso J, HampdenSmith MJ (1997) Comparison of solid-state and spray-pyrolysis synthesis of yttrium aluminate powders. J Am Ceram Soc 80 1231-1238... 

CNTs can also be made using natural precursors. For example, castor oil was the carbon source used in the spray pyrolysis synthesis of CNTs from a castor oil-FcH solution at 850 °C under an Ar atmosphere [32]. 

Huang, Y, K. Deng, Z. Ai, and L. Zhang, Ultrasonic spray pyrolysis synthesis and visible hght activity of carbon-doped TiojiZroc Oj solid solution photocatalysts. Mater. Chem. Phvs. 114 (2009) 235-241. 

Fig 12.4 Schematic diagram of the experimental apparatus for ultrasonic spray pyrolysis synthesis. Reproduced with permission from [45]. Copyright 2002 Elsevier... 

Zhao C, Krall A, Zhao H, Zhang Q, Li Y (2012) Ultrasonic spray pyrolysis synthesis of AgATi02 nanocomposite photocatalysts for simultaneous H2 production and CO2 reduction. Int J Hydrog Energy 37 9967-9976... 

Although the CFCs and HCFCs are not as stable as the PFCs, they still can be rather stable compounds (3,11)- Dichlorodifluoromethane, CCI2F2, is stable at 500°C in quartz CCl F and CHCIF2 begin to decompose at 450 and 290°C, respectively (7). The pyrolysis of CHCIF2 at 650—700°C in metal tubes is the basis of a commercial synthesis of tetrafluoroethylene ... 

Vlayl fluoride [75-02-5] (VF) (fluoroethene) is a colorless gas at ambient conditions. It was first prepared by reaction of l,l-difluoro-2-bromoethane [359-07-9] with ziac (1). Most approaches to vinyl fluoride synthesis have employed reactions of acetylene [74-86-2] with hydrogen fluoride (HF) either directly (2—5) or utilizing catalysts (3,6—10). Other routes have iavolved ethylene [74-85-1] and HF (11), pyrolysis of 1,1-difluoroethane [624-72-6] (12,13) and fluorochloroethanes (14—18), reaction of 1,1-difluoroethane with acetylene (19,20), and halogen exchange of vinyl chloride [75-01-4] with HF (21—23). Physical properties of vinyl fluoride are given ia Table 1. 

Chemicals have long been manufactured from biomass, especially wood (sHvichemicals), by many different fermentation and thermochemical methods. For example, continuous pyrolysis of wood was used by the Ford Motor Co. in 1929 for the manufacture of various chemicals (Table 20) (47). Wood alcohol (methanol) was manufactured on a large scale by destmctive distillation of wood for many years until the 1930s and early 1940s, when the economics became more favorable for methanol manufacture from fossil fuel-derived synthesis gas. 

Pyrolysis ofVegetals. Many pubhcations concern the synthesis of dihydroxybenzenes by wood, lignites, and tree bark pyrolysis (61). The selective extraction of these compounds in low concentration from the cmde mixture remains a significant problem. So far, the price of the extraction overcomes the advantage of starting from a cheap starting material. 

Propylene Dimer. The synthesis of isoprene from propjiene (109,110) is a three-step process. The propjiene is dimeri2ed to 2-methyl-1-pentene, which is then isomeri2ed to 2-methyl-2-pentene in the vapor phase over siUca alumina catalyst. The last step is the pyrolysis of 2-methyi-2-pentene in a cracking furnace in the presence of (NH 2 (111,112). Isoprene is recovered from the resulting mixture by conventional distillation. 

Synthesis From Other Ring Systems. These syntheses are further classified based on the number of atoms in the starting ring. Ring expansion of dichlorocyclopropane carbaldimine (53), where R = H and R = ryl, on pyrolysis gives 2-arylpyridines. Thermal rearrangement to substituted pyridines occurs in the presence of tungsten(VI) oxide. In most instances the nonchlorinated product is the primary product obtained (63). 

Synthesis. Iminoboranes, thermodynamically unstable with respect to oligomerization can be isolated under laboratory conditions by making the oligomerization kineticaHy unfavorable. This is faciUtated by bulky substituents, high dilution, and low temperatures. The vacuum gas-phase pyrolysis of (trimethylsilylarnino)(aLkyl)haloboranes has been utilized as an effective method of generating iminoboranes RB=NR as shown in equation 19 for X = F,... 

Iminoboianes have been suggested as intermediates in the formation of compounds derived from the pyrolysis of azidoboranes (77). The intermediate is presumed to be a boryl-substituted nitrene, RR BN, which then rearranges to the amino iminoborane, neither of which has been isolated (78). Another approach to the synthesis of amino iminoboranes involves the dehydrohalogenation of mono- and bis(amino)halobotanes as shown in equation 21. Bulky alkah-metal amides, MNR, have been utilized successfully as the strong base,, in such a reaction scheme. Use of hthium-/i /f-butyl(ttimethylsilyl)amide yields an amine, DH, which is relatively volatile (76,79). 

A convenient laboratory synthesis of high purity CA is hydrolysis of cyanuric chloride (7). On a commercial scale, CA is produced by pyrolysis of urea [57-13-6]. When urea is heated at - 250 ° C for about an hour, it is converted to crude CA with evolution of ammonia. 

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