Carbonate conversions

The term allylic refers to a C=C—C unit The singly bonded carbon is called the allylic carbon, and an allylic substituent is one that is attached to an allylic carbon Conversely doubly bonded carbons are called vinylic carbons, and substituents attached to either one of them are referred to as vinylic substituents... 

Another hydrogenation process utilizes internally generated hydrogen for hydroconversion in a single-stage, noncatalytic, fluidized-bed reactor (41). Biomass is converted in the reactor, which is operated at about 2.1 kPa, 800°C, and residence times of a few minutes with steam-oxygen injection. About 95% carbon conversion is anticipated to produce a medium heat value (MHV) gas which is subjected to the shift reaction, scmbbing, and methanation to form SNG. The cold gas thermal efficiencies are estimated to be about 60%. 

More recendy, advanced generation gasifiers have been under development, and commercialisation of some of the systems has become a reaUty (36,41). In these newer developments, the emphasis has shifted to a greater throughput, relevant to the older gasifiers, and also to high carbon conversion levels and, thus, higher efficiency units. 

The first stage assures high carbon conversion and optimum slag removal. The second stage reduces the raw product gas temperature to about 1000°C. This latter step helps to improve cold gas efficiency relative to other slurry fed processes and to lower waste heat recovery costs (15—18). 

C. Oxygen and steam are also injected above the bed to increase carbon conversion and reduce yields of methane and other hydrocarbons. The freeboard 2one above the bed operates as much as 150 to 230°C above the bed temperatures (24). 

Carbon Conversion. Carbon conversion on a once-through basis is a function of the coal composition and is strongly influenced by the oxygen/coal ratio. For some coals, the conversion pattern is also affected by the level of steam in the blast. Another factor is fly slag recycle, which raises the carbon conversion by recycling the unconverted carbon, most of which resides on the fly slag. This results in an overall carbon conversion greater than 99%. 

In principle both AHD and AHB can be obtained from Equation 14, using data for the conversion of available carbon to C02 at two different temperatures. In practice, however, this calculation does not yield reliable values because of the very small range of carbon conversion available under our experimental conditions and because of the very large difference in magnitude of the two enthalpies. 

The Shell syngas contains about 80-83% of the energy in the coal feed (the cold gas efficiency). This high efficiency is due to the high carbon conversion (>96%) during gasification (Tables 3.4 through 3.6).5... 

The mass and heat balances of the process are satisfactory when coal is gasified to a 53% carbon conversion in the gasifier and the remaining 47% of carbon is sent to the regenerator. From the heat values of the produced fuel gas and the input coal, the cold-gas efficiency (91 vol% H2 with 9 vol% CH4 298 K, 0.1 MPa) was calculated to be higher than 0.77. 

Cyclic carbonate ROH Cyclic carbonate conversion (mol%) DMC selectivity (mol%)a DPC selectivity (mol%)a... 

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