Sulfur and Nitrogen Compounds

The organic nitrogen compounds are converted to ammonia which, if allowed to build up in die recycle gas, competes with the hydrocarbon for the active catalyst sights. This results in a lower apparent activity of the catalyst as the ammonia concentration increases. Because of this, feedstocks with high organic nitrogen contents are more difficult to process and require higher catalyst temperatures 

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Calculation of group increments for oxygen, sulfur and nitrogen compounds has allowed the estimation of conventional ring-strain energies (CRSE) for saturated heterocycles from enthalpies of formation. For 1,3-dioxolane, CRSE is about 20 kJ mol . In 2,4-dialkyl-l,3-dioxolanes the cis form is always thermodynamically the more stable by approximately 1 kJ mol" . 

Reactions occurring in hydrotreatment units are mainly hydrodesulfurization and hydrodenitrogenation of sulfur and nitrogen compounds. In... 

Unlike sulfur and nitrogen compounds in air where we found a wide range of oxidation states in relatively few compounds, carbon has a nearly unlimited number of compounds. These... 

Other sinks - largely biological - probably exist at the Earth s surface. Seiler (1974) deduced a lifetime of ca. 0.5 year for CO, attesting to the lack of reactivity or water solubility in comparison to sulfur and nitrogen compounds. 

We have only recently understood the phenomena that control rainwater pH in the natural, unpolluted environment. As pointed out in Section 16.2, these appear to be mainly the cycles of sulfur and nitrogen compounds. A model of the unperturbed system is necessary in order to understand and predict the changes that occur when strong sulfur- and nitrogen-acids are... 

Direct conversion of target compounds (sulfur and nitrogen compounds, hydrogen sulfide, polyaromatics, etc.) to an easily removable or desirable product. 

ISAL A hydrotreating process for removing sulfur and nitrogen compounds from petroleum fractions without reducing their octane values. Developed by Intevep SA, the research and technology arm of Venezuela s state petroleum company PDVSA. A proprietary zeolite catalyst first saturates the olefins and then isomerizes them to higher octane-value compounds. 

MRH (2) A hydrocracking process for difficult petroleum residues, i. e., those containing high levels of metals, sulfur, and nitrogen compounds. It uses catalytic hydrogenation in a slurry bed. Developed by the MW Kellogg Company. 

Unisol A process for extracting organic sulfur and nitrogen compounds from petroleum fractions by solvent extraction with aqueous sodium or potassium hydroxide containing... 

The OPLS parameters (charges and Lennard-Jones terms) were obtained primarily via Monte Carlo simulations with particular emphasis on reproducing the experimental densities and heats of vaporization of liquids. Those simulations were performed iteratively as part of the parametrization, so better agreement with experiment is obtained than in previous studies where the simulations were usually carried out after the parametrization. Once the OPLS parametrization was completed, further simulations were also performed in order to test the new set of parameters in the calculation of other thermodynamic and structural properties of the system, besides its density and its heat of vaporization. Parameters have now been generated, among others, for water, alkanes, alkenes, alcohols, amides, alkyl chlorides, amines, carboxylic esters and acids, various sulfur and nitrogen compounds, and nitriles. A protein force field has been established as well. 

Many processes in a refinery use steam as a stripping medium in distillation and as a diluent to reduce the hydrocarbon partial pressure in catalytic or thermal cracking [37]. The steam is eventually condensed as a liquid effluent commonly referred to as sour or foul water. The two most prevalent pollutants found in sour water are H2S and NH3 resulting from the destmction of organic sulfur and nitrogen compounds during desulfurization, denitrification, and hydrotreating. Phenols and cyanides also may be present in sour water. 

Phenolic, Sulfur, and Nitrogen Compounds in Food Flavors Charalambous, G. Katz, I., Eds. ACS Symposium Series No. 26 American Chemical Society Washington, DC, 1976. 

Evers WJ, Heinsohn HH, Mayers BJ, Sanderson A (1976) In Charalambous G, Katz I (eds) Phenolic, Sulfur and Nitrogen Compounds in Food Flavors. ACS Symposium Series 26. American Chemical Society, Washington, p 184... 

Acid rain Rain or any other form of precipitation that is strongly acidic due to sulfur and nitrogen compounds released through the burning of fossil fuels, particularly coal. 

The requirement of chemical stability will be appreciated when it is considered that the catalyst is exposed during the cracking step to hydrocarbon vapors, sulfur and nitrogen compounds, and water vapor. During the regeneration step it is exposed to sulfur dioxide, carbon monoxide, carbon dioxide, water vapor, and possibly nitrogen compounds in addition to air. 

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