Energy & Fuels 1991,5,753-760
with both DMP and 3-MI model compounds. DMP and 3-MI are themselves deleterious to fuel stability. Interactive studies with DMP and acid species codopants show that the maximum insolubles were 1323.6 mg/lOO mL fuel for the high DMP/high DBSA experimental set, and the least insolubles were for low DMP/low HOAc, 57.4 mg/lOO mL fuel set. For 3-MI interactive runs,a similar trend but with much lesa sediment was observed. For example, with the high 3-MI/high DBSA mixture, the maximum sediment observed was 69.7 mg/100 mL fuel. The results clearly indicate tha the acid species, especially sulfonic acids, function as both a catalyst and radical initiator and in the case of dodecylbenzenesulfonic acid functions in a minor role as a reactant in sediment formation when either
753
DMP or 3-MI is inducing instability in a shale-derived diesel fuel. For the low DMP/high DBSA matrix, only a small quantity of sediment was observed to form (1.5 mg/100 mL fuel). The strongly acidic DBSA was found to dissolve the sediment formed from the DMP. In an earlier study with tert-butyl hydroperoxide? no incorporation of the oxygen moieties from this dopant was found in the sediment that subsequently formed. In this study employing acid codopants MS and IR data indicate that trace amounts of the sulfonic acid were incorporated into the sediment. Registry No. DMP,62584-3;%MI,83-34-1;pTsOH, 106154; DBSA, 27176-87-0;HOAC, 64-19-7;HA, 142-62-1.
Decomposition of Ammonia over Dolomite and Related Compounds Eva Bjorkman* Studsvik AB, S-611 82 Nykoping, Sweden
Krister Sj ostr om The Department of Chemical Technology, Royal Institute of Technology, S-100 44 Stockholm, Sweden Received December 20, 1990. Revised Manuscript Received May 31, 1991 The decomposition of ammonia in fuel gas is desirable, since the ammonia can be oxidized to nitrogen oxides during combustion, thus contributing to the emission. On calcined dolomite (CaMgO,), ammonia can decompose almost quantitatively in an inert atmosphere. Pure CaO and MgO also affected the reaction but to a smaller amount. CaO contributed much more than MgO. The activity of calcined dolomite cannot be explained by additive effect from its main constituents or by its larger surface area as compared to other materials. The composition of the surrounding atmosphere is of importance for the ammonia decomposition reaction. The presence of hydrocarbons (CHI and C2H4), which can form carbonaceous material on dolomite inhibited the decomposition reaction. Hydrogen decreased the reaction rate, probably due to equilibrium reactions. Steam inhibited the ammonia decomposition reaction.
Introduction The fuel gas that is produced in gasification processes contains, among other products, tar and combustible nitrogen compounds. The tar concentration can effectively be reduced if the fuel gas passes through a bed of dolomite1i2but it is not known in which way the dolomite influences the concentration of the nitrogen compounds. Depending of the fuel, the nitrogen is combined with carbon in different types of bonds. At gasification temperatures, C-C bonds are readily broken, but the C-N bonds survive. Thus, HCN is the initial nitrogen-bearing gaseous product of pyrolysis. In a gasifier, the oxygen potential and the temperature near the inlet are sufficiently high to convert the HCN, through an NH, intermediate, to NO and N2 As the gases travel through the ~
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(1) Alden, H.;Espenb, B. G.;Rensfelt, E. International Conference on Reuearch rn Thermochemical Biomass Conoersion; Elsevier: New York, 1988, p 987. (2) Sjd+r6m, K.; Tarale, G.;L i i i i , L. International Conference on Reuearch rn Thermochemrcal Biomoes Conoeruion; Elsevier: New York, 1988; p 974.
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Table I. Chemical Analysis of Dolomite (wt W ) Ca 22.0 Mn 0.06 MI3 12.9 P
