Autogenic method

In the autogeneous method, the specimens are subjected to heat due to the hydration of cement in a completely insulated environment over a period of 48 hours. 

Another option would be to employ an alternative method for plastic carboiuzation that would overcome the problem of low yields posed by classic carboiuzation and activation methods. A possible route would be the employment of pressurized pyrolysis. For purposes other than activated carbon production, hydrocarbon precursors have been heated under pressure to produce solid carbon products with high yields and high purity [92-94]. As an example, exceptionally hard carbon microspheres have been produced from PET waste via the closed autoclave method. This autogenic method has been patented for the production of carbon spheres for use in batteries [95]. Pol et al. further explained their method in a more extensive article [96]. In order... 

On the other hand, if only solid carbon products are sought, high pressure pyrolysis could potentially be used. Although hard non-porous spheres have been repeatedly produced by this method, further research is needed to assess the possibility of obtaining porous carbons. The lack of diverse literature regarding the use of plastic wastes as precursors of autogenic methods leaves the door open for further investigations. 

Pure zirconium tetrachloride is obtained by the fractional distillation of the anhydrous tetrachlorides in a high pressure system (58). Commercial operation of the fractional distillation process in a batch mode was proposed by Ishizuka Research Institute (59). The mixed tetrachlorides are heated above 437°C, the triple point of zirconium tetrachloride. AH of the hafnium tetrachloride and some of the zirconium tetrachloride are distiUed, leaving pure zirconium tetrachloride. The innovative aspect of this operation is the use of a double-sheU reactor. The autogenous pressure of 3—4.5 MPa (30—45 atm) inside the heated reactor is balanced by the nitrogen pressure contained in the cold outer reactor (60). However, previous evaluation in the former USSR of the binary distiUation process (61) has cast doubt on the feasibHity of also producing zirconium-free hafnium tetrachloride by this method because of the limited range of operating temperature imposed by the smaH difference in temperature between the triple point, 433°C, and critical temperature, 453°C, a hafnium tetrachloride. 

High dediazoniation temperatures can also be obtained by conducting the reaction in an autoclave under autogenous or applied super-atmospheric pressures.36-59-63-64 Though less efficient in some cases than the methods above, this technique is far simpler. Some results are shown for the formation of 7. 

The method has been applied by the submitters2 to the preparation of cyclohexylmethylpropiolaldehyde diethyl acetal (54% yield) from cyclohexylmethylacetylene and triethyl orthoformate of phenylethynyl n-butyl dimethyl ketal (40% yield) from phenylacetylene and trimethyl -orthovalerate and of phenylethynyl methyl diethyl ketal (34% yield) from phenylacetylene and triethyl orthoacetate. w-B utylpropiolaldehyde diethyl acetal was isolated in 32% yield by heating an equimolar mixture of 1-hexyne and triethyl orthoformate containing catalytic amounts of a zinc chloride-zinc iodide catalyst under autogenous pressure at 190° for 3 hours. 

Polymer crystals grown from silica gel at room temperature contain 1-D chains of [Er(TMA)(H20)5]n,[4] The use of a highly controlled layer diffusion method gives 2-D [ErfTMA)(H20)3]n. In this material loss of two ancillary aqua groups allows pendant carboxylates of adjacent 1-D polymer strands to connect and create a sheet. Finally the use of hydrothermal conditions (180°C, autogenous pressure. 3 days) allows formation of anhydrous [Er(TMA)]n. This has a 3-D network with no simple topological relationship to the hydrated forms.[5]... 

The supported Cu/Ce02 catalyst (denoted here as Cu/Ce-CTAB) was hydrother-mally prepared using Ce and Cu nitrates as precursors with a surfactant, CTAB [90], In a typical synthesis method, Ce(N03)3 6H20 was dissolved in hot distilled water, to which Cu(N03)2 3H20 in H20 was added dropwise. Then, CTAB was dissolved in a mixture of H20 and ethanol, and the obtained solution was added to the Cu + Ce solution. The typical molar composition is Cu/CTAB/H20 = 1.0 0.55 325. The homogeneous slurry mixture was hydrothermally treated at 175 °C for 24h in a Teflon-lined autoclave vessel under an autogeneous pressure. The resultant product was washed with distilled H20 and EtOH, and dried at ambient temperature for 10 h and then at 100 °C for 8h, followed by heating at 500°C for 6h under a He flow. The Cu contents of the obtained solid catalysts were determined by XRF. 

This paper presents a new method for preparing 1,2-bis-(dichlorophosphino)alkanes based on the reaction of unsaturated hydrocarbons with PCl and elemental phosphorus at 180-250°C under autogenous pressureI. The basic reaction with ethylene is... 

The practical scope of our new method for preparing 1,2-bis-(dichlorophosphino)alkanes using the ratio of alkene to elemental phosphorus shown in eq 1 and a 50-150% excess of PCI- at 200-250°C for 4-6 hours under autogenous pressure is shown in Table I. 

Zeolites are normally prepared by crystallization (precipitation) in hydrothermal conditions (T = 350-525 K) of (Si,Al)-containing hydrogels [3]. Above 373 K, crystallization is normally performed under autogeneous pressure. Both batch and continuous synthesis methods can be envisaged. Variables which affect the synthesis of zeolites fall into 3 categories ... 

Unmixed zones. All methods of welding stainless steel with a filler metal produce a weld fusion boundary consisting of base metal that has been melted, but not mechanically mixed with filler metal and a partially melted zone in the base metal. An unmixed zone has the composition of base metal, but the microstructure of an autogenous weld. The microsegregation and precipitation phenomena characteristic of autogenous weldments decrease the corrosion resistance of an unmixed zone relative to the parent metal. Unmixed zones bordering welds made from overalloyed filler metals can be preferentially attacked when exposed on the weldment surface.14,61... 

An alternative preparative method is available in this instance also (see later). The hexafluoroplatinate NF4PtF6 is formed in high yield when PtF6 is treated with a large excess of NF3 and F2 at 125°C under an autogeneous pressure of about 140 atm (65). A less pure sample was obtained by oxidizing a mixture of NF3 and PtF6 with a KrF+ salt (see later). 

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