Naphtha aromatization is difficult to “scale up””

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Anxunsisi Author: Anxunsisi—Yan Rijuan July 6: In the first quarter of 2016, several aromatization units in Shandong and its surrounding areas switched to naphtha aromatization. However, Anxunsisi believes that it may be difficult to replicate the \"large-scale\" application of naphtha aromatization compared to the carbon four aromatization process using ethers. Easy availability of raw materials, coupled with profit motives, led to the emergence of groups dedicated to naphtha aromatization. Starting in 2009, aromatization units grew rapidly, and a large number of such units were established in a short period of time. However, with the development of advanced processing, alkylation has essentially replaced aromatization. As a result, starting from the second half of 2013, the operating rate of aromatization units in Shandong and surrounding areas remained at extremely low levels for an extended period. Aromatization units also face the fate of being left idle for long periods or having to be demolished. In the first half of 2016, nearly 10 ether-derived C4 aromatization units in Shandong and surrounding areas such as Lushenfa, Yuxiang, and Henan Yongsheng were converted into naphtha aromatization units. The unit built by Hebei Jiujiu Industry and Trade a few years ago is also under evaluation for potential operation. It is understood that the reasons for this situation are as follows: 1. Naphtha is easier to obtain than ether-derived C4 and its price is relatively low. For the further processing of ether-derived C4, the biggest constraint on its development has always been the insufficient supply of this raw material. Thanks to advantages such as high product yield, good quality of the oil products, and low cost pressures, alkylation has essentially captured all the C4 feedstocks available on the market after etherification. At present, as the quality and quantity of crude oil processed by local refineries have improved, the production of naphtha has increased accordingly; however, the processing capacity is insufficient, resulting in excess naphtha entering the market, which lays the foundation for the renovation of naphtha aromatization units. Moreover, its price is more competitive than that of post-ether tetrahydrocarbons; taking the transactions in Shandong region on July 6 as an example, the mainstream price for post-ether tetrahydrocarbons was 3,340–3,420 yuan per ton, while the price for naphtha was around 3,200 yuan per ton. 2. The yield of aromatized oil increases, altering the profit situation. In aromatization units that use carbon tetrafluoride as raw material, the yield of aromatized oil is around 35%, with the remainder being clean gas; due to the low yield of the main product, these aromatization units have been operating at a loss for a long time. Taking the Shandong region as an example, data from Anxunsi show that since the second half of 2013, aromaticization units have been operating at a loss. After being modified to use naphtha as the main raw material, the yield of aromatized oil can range from 60% to 90%, depending on the proportion of naphtha fed in. At the same time, the profit situation of the device has also changed. A staff member from a company in Shandong said, “In April and May, for every ton of aromatized oil produced by the naphtha aromatization unit, the profit is between 200 and 300 yuan.” ； The oil market is currently sluggish, but it at least ensures no losses. ” Furthermore, the modification of the plant is not difficult; it only requires adding a naphtha feed line to the existing aromatization unit and replacing the catalyst. No changes are required for the remaining pipelines and reactors. Constraints on naphtha aromatization remain. Although, in the short term, naphtha aromatization has enabled previously \"disused\" aromatization units to be put back into use, there are still many constraints that limit its further development. First, in terms of products: naphtha aromatization products have a low octane number, a reduced vapor pressure, and a high olefin content, which is contrary to the requirement of upgrading oil products to improve their quality. Second, in terms of raw material types: Building on the first point, in order to meet the standards for National V 90# gasoline, naphtha aromatization plants keep the octane rating of their products at around 82. As a result, it is not possible to use naphtha alone as a raw material; instead, it must be mixed with an appropriate amount of tetrahydrocarbon derivatives (most plants use a 1:1 ratio, and the more naphtha that is used, the lower the octane rating and vapor pressure of the product). As mentioned earlier, the supply of most tetra-carbon compounds derived from ethers has already been taken over by companies engaged in activities such as alkylation and isomerization; it is quite difficult for naphtha aromatization to secure a share of this market. Regarding the supply of naphtha, it is currently sufficient, but in the future, as local refineries build or plan to build units for reprocessing, incomplete statistics show that alone in the Shandong region the capacity will reach 13.6 million tons per year, which will lead to a shortage of naphtha supplies. Therefore, overall, naphtha aromatization has certain advantages in terms of profits and raw materials, but caution is still needed in the long term to avoid repeating the mistakes made with tetrahydrocarbon aromatization after ether production.