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Isooctane is a valuable octane enhancer for gasoline and the primary component of aviation gasoline, also known as Avgas, because of its high antiknock quality. Conventional industrial processes for isooctane production involve the steps of dimerization of isobutene, dimer separation, and hydrogenation. The efficacy of catalytic distillation (CD) and its merits, in terms of energy savings and reduction of greenhouse gas emissions, for the production of isooctane are quantitatively presented. The feed considered for the isooctane production is composed of isobutene (C4) and inerts (isopentane) produced in refineries as byproducts of steam cracking of naphtha and light gas oil. Process flow sheets for the two routes for the production of isooctane, with and without CD, are modeled. The conventional industrial flow sheet composed of a dimerization reactor, distillation column, and a hydrogenation reactor (configuration A), is simulated using Aspen Plus. The intensified process flow sheet comprising a CD column for the dimerization, hydrogenation, and separation (configuration B) is modeled using gPROMS. A validated, nonequilibrium, three-phase model is developed in a gPROMS environment and is used to quantify the energy savings and reduction of carbon dioxide emissions achieved using a CD column for the intensified process. Results demonstrate CD to be a promising candidate to replicate the conversions and product purity obtained in the conventional process while resulting in significant energy savings, more efficient utilization of isobutene feed, and reduced carbon dioxide emissions.

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Nanoparticles of SiO2 have been produced in an inductively coupled thermal plasma reactor. The resulting nanoparticles were characterized based on their morphology and size distribution. Scanning electron microscopy, nitrogen absorption (BET method), laser diffractometry and X-ray diffraction techniques were used to characterize and to measure the equivalent diameter (D(1,0), D(3,2) and D(4,3)) of the resulting nanopowders. The computational fluid dynamics (CFD) software FluentTM 6.1 with the Fine Particle Model (FPMTM) was used to simulate the whole synthesis process. The nanoparticles of SiO2 produced at the exit (filter) and on the reactor wall had primary particles diameter between 10-300 nm while the aggregates were of much larger size, between 1 and 4 micrometers. The simulation predictions were used to gain more insight into the experimental results.

Since water shortage has been a serious challenge in Iran, long-term investigations of alternative water resources are vital. In this study, we performed long-term (1979–2018) model simulation at seven locations (costal, desert, mountain, and urban conditions) in Iran to investigate temporal and spatial variation of dew formation. The model was developed to simulate the dew formation (water and ice) based on the heat and mass balance equation with ECMWF-ERA-Interim (European Centre for Medium-Range Weather Forecasts–Re-Analysis) meteorological data as input. According to the model simulation, the maximum mean yearly cumulative dew yield (~65 L/m2) was observed in the mountain region in the north part of Iran with a yearly mean cumulative dew yield was ~36 L/m2. The dew yield showed a clear seasonal variation at all selected locations with maximum yields in winter (mean monthly cumulative 3–8 L/m2 depending on the location). Here we showed that dew formation is frequent in northern Iran. In other areas, where there was suffering from water-stress (southern and central parts of Iran), dew can be a utilized as an alternative source of water. The dew yield during 2001–2014 was lower than the overall mean during the past 40 years a result of climate change in Iran.

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