Synthesis and utilization of non-metallic detergent/dispersant and antioxidant additives for lubricating engine oil Amal M. Nassar a , Nehal S. Ahmed a , Hamdy S. Abdel-Hameed a,n , Ahmed F. El-Kafrawy b a Department of Petroleum Applications, Egyptian Petroleum Research Institute, Nasr City, Cairo, Egypt b Chemistry Department, Faculty of Science, Ain Shams University, Abbasiya, Cairo, Egypt article info Article history: Received 11 June 2015 Received in revised form 1 August 2015 Accepted 18 August 2015 Available online 10 September 2015 Keywords: Lubricating oil additives Ashless detergents and dispersants Antioxidants Propylene oxide abstract In the present work, different ashless detergent/dispersant additives based on propylene oxide (PO) were prepared via reaction of propylene oxide with different tertiary amines and the products which obtained were reacted with different organic acids. The structures of the prepared compounds were confirmed using fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance ( 1 H NMR) and gel permeation chromatography (GPC) for determination of molecular weight. All the prepared com- pounds were found to be soluble in lubricating oil. The efficiency of the prepared compounds as anti- oxidants and detergent/dispersant additives for lubricating oil was investigated. It was found that the additives have excellent power of dispersion, detergency and the most efficient additives as antioxidant those prepared by using n,n-dimethyloctadecylamine and di-n-butyl dithio phosphoric acid. & 2015 Elsevier Ltd. All rights reserved. 1. Introduction The development of lubricants has become an integral part of the development of machinery and its corresponding technologies. It is irrevocably and interdisciplinarily linked to numerous fields of expertize and without this interdisciplinary aspect, lubricant developments and applications would fail to achieve success [1]. Additives are synthetic chemicals used to improve different lubricant parameters, they can boost existing properties, eliminate adverse characteristics, or introduce new properties in the base oil. They can be added to base oils at percentage levels up to 5–30% of total weight [2]. At low temperature, the lubricant is expected to flow sufficiently in order that moving parts are not starved of oil. At high temperature, they are expected to keep the moving parts separated to minimize wear. The formation and accumulation of carbon deposits in the intake valves and ports of the fuel system during the operating of an internal combustion engine, is a com- mon problem, which result in a decrement of the operational efficiency of the engine, due to these deposits restricting the flow of air–fuel entering the combustion chamber. The reduction of deposit levels has been the result of uses the detergent / dis- persant additives [3]. Detergents and dispersants, often called DD or HD (heavy-duty) additives have been indispensable for the development of modern engine oils for gasoline and diesel combustion motors. Deter- gents are the metal salts of organic acids [4, 5]. The acids norm- ally used to synthesize these compounds include arylsulfonic acids such as alkylbenzenesulfonic acids and alkylnaphthalenesulfonic acids; alkylphenols; carboxylic acids such as naphthenic acids, and petroleum oxidates; and alkenylphosphonic and alkenylthiophosphonic acids. Dispersant molecules are added to disperse the largely carbo- naceous particulate by-products of the combustion process and engine oil degradation. This solid material leads to the formation of ‘‘sludge’’ in petrol engines (‘‘soot’’ in diesel engines) which comprises both organic and inorganic components, accumulation of which can cause engine damage through wear and oil filter [6]. There are four different types of ashless dispersants: (1) succini- mide, (2) succinate esters, (3) mannich types and (4) phosphorus types [7]. The lubricating oils consist of hydrocarbons with (C 20 –C 70 ) carbon atoms. At higher temperature these hydrocarbons are oxidized to form acids, alcohols, aldehydes, ketones, esters and peroxides. All these compounds form the solid asphaltic materials. For this reason, the addition of antioxidants is necessary to all lubricating oils to minimize the formation of such compounds [8,9]. As the role of antioxidants is to protect the type of base oil by either scavenging (alkyl and peroxy) radicals, or decomp- osing hydroperoxides into stable products [10,11]. The present work aims to preparation of different ashless detergent/disper- sant additives based on propylene oxide and evaluation of the prepared compounds as antioxidant and detergent/dispersant for lubricating oil. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/triboint Tribology International http://dx.doi.org/10.1016/j.triboint.2015.08.033 0301-679X/& 2015 Elsevier Ltd. All rights reserved. n Corresponding author. Tel.: þ202 22747847; fax: þ202 22747433. E-mail addresses: dr_hamdy5@yahoo.com, hamdysayed89@gmail.com (H.S. Abdel-Hameed). Tribology International 93 (2016) 297–305