Green route for carbonylation of amines by CO2 using Sn-Ni-O bifunctional catalyst and theoretical study for finding best suited active sites

[Display omitted] •Good correlation of acid-base sites of Sn-M − O with catalytic activity is obtained.•Sn-Ni-O is a robust and reusable catalyst for substituted urea synthesis.•Acid-base sites are tuned by dispersion of SnO2 on NiO for this reaction.•A new theoretical model is developed to design b...

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Bibliographic Details
Published in:	Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 419; p. 129439
Main Authors:	Kulal, Nagendra, Vetrivel, Rajappan, Gopinath, Chinnakonda S., Ravindran, Rahul K., Rao, Vinod N., Shetty, Manjunath, Shrikanth, R., Rangappa, Dinesh, Shanbhag, Ganapati V.
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-09-2021
Subjects:	Amines CO2 Mixed oxide catalyst and bi-functional catalyst Substituted urea Amines Substituted urea Mixed oxide catalyst and bi-functional catalyst CO2
Online Access:	Get full text
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Summary:	[Display omitted] •Good correlation of acid-base sites of Sn-M − O with catalytic activity is obtained.•Sn-Ni-O is a robust and reusable catalyst for substituted urea synthesis.•Acid-base sites are tuned by dispersion of SnO2 on NiO for this reaction.•A new theoretical model is developed to design better acid base catalyst.•The equations can be used to predict the product yield with known active sites. Reaction between n-alkylamine and CO2 has gained interest due to the demand for the dialkylurea for various applications. For the first time, the tool Mathematica was used to analyze the experimental data with an idea to derive an equation which determines the best suited active sites for any given input set of dependent parameters. The equation can further be used to predict the product yield with the known values of active sites for a reaction. Among several Sn containing mixed oxides, Sn-Ni oxide (Sn-Ni-O) was found to be the better performing catalyst. The studies indicate that the formation of new defect sites when NiO and SnO2 are in the mixed state and possibly a solid solution enhances the catalytic efficiency. There are two main reasons for improved catalytic performance; one, mixing of SnO2 into NiO which reduces the number of holes (h+) localized on lattice oxygen (O2−+ h+→ O•−) and two, smaller SnO2 particles are dispersed on the bigger particle NiO which alters the acidic and basic active sites in the catalyst. FT-IR adsorption study with amine and CO2 helped in deriving a plausible mechanism for this reaction. Under optimized reaction condition, Sn1.1-Ni-O-600 gave 77.3% of n-butylamine conversion and 75.7% of yield for 1,3-dibutylurea. The versatility of the catalyst was tested for carbonylation of different aliphatic and aromatic amines, diamine and hydroxy amine with CO2.
ISSN:	1385-8947 1873-3212
DOI:	10.1016/j.cej.2021.129439