Plant Asphalt has broad prospects for development

Petrochemical bitumen is a scarce, non-renewable resource. With the depletion of petroleum resources, people must look for alternatives or a renewable and environmentally friendly bitumen to achieve sustainable development goals.

First, the scarcity of asphalt resources has begun to restrict the construction of China's huge road network

According to the National Highway Network Plan under implementation, China plans to reach 85,000 kilometers of expressways nationwide by 2020. Last year, the mileage of highways in China reached 74,000 kilometers, and it is expected that the planned mileage will be basically completed by the end of 2011. By then, cities with a population of more than 200,000 in China will all be connected by highways.

The huge road network construction plan in China has created a huge demand for road asphalt. In 2010, the apparent consumption of bitumen in China exceeded 20 million tons, of which, 16.26 million tons of bitumen and 4.1 million tons of imported bitumen hit a record high, and at the same time the prices of asphalt increased, exceeding 5,000 yuan/ton. Level. It can be foreseen that the import dependence of asphalt will surely increase further.

With the depletion of petroleum resources and the rising prices of asphalt, it has begun to constrain the sustainable development of China’s road construction. At present, as a mature alternative to asphalt, cement, although it can play a certain role in urban roads, cement is not suitable for highway use. Its comfort, vehicle safety, road surface swelling performance, and road surface settlement are all factors. It is difficult to completely replace the use of asphalt.

In addition, petrochemical bitumen has the disadvantage of being non-degradable and the utilization rate of waste asphalt produced from the renovation of the road surface is very low and it is difficult to handle. In the process of use, asphalt smoke also contains a large number of carcinogenic substances, polluting the environment, while emitting large amounts of carbon dioxide. At home and abroad, many experts are dedicated to the research and development of "petrochemical bitumen temperature mixing technology". The processing temperature is controlled within 130 degrees Celsius by using solvents or surfactants to prevent the generation of smoke, but the technology is still costly and difficult to implement on a large scale. Promote use.

Second, plant refining asphalt market still needs to be cultivated

At present, most of the vegetable asphalt that appears in the market is waste after refining vegetable oil, accounting for about 3 to 5% of the total vegetable oil fraction. Its main component is 60-80% of fatty acids and plant alcohols. Its oil solubility is close to that of asphalt. It is mainly used in the fields of foundry adhesives and waterproof asphalt, or directly burned as heavy oil fillers.

In 2010, the output of domestic vegetable oil was approximately 39 million tons, and more than 1,000 companies engaged in vegetable oil processing. Based on the above-mentioned ratios, the annual output of vegetable asphalt is approximately 117 to 1.95 million tons. Due to the wide distribution, poor quality, and limited collection and transportation costs, it has been difficult to use them to date. Therefore, most of the domestic experts and scholars have focused on the redevelopment and utilization of plant-refined asphalt, hoping to further extract some useful organic acids or sterols from the oil foot, and rarely think about its application from the viewpoint of asphalt substitution. Related Articles Also rarely reported.

In 2009, experts from the British Materials Industry Association used vegetable vegetal (Vegetex) instead of 20% of the bitumen required for paving asphalt roads and achieved success. This kind of bitumen not only has the concept of renewable, but also can be processed at low temperature, with lower energy consumption, reducing the solvent on which the “warming asphalt technology” relies, and reducing costs.

Third, the bio-chemical industry has opened up a new idea for the development of renewable environmental protection asphalt

Although experts in the United Kingdom can technically develop vegetable asphalt that can replace petrochemical bitumen, it is difficult to achieve great results due to raw material and market restrictions. In comparison, China has abundant renewable plant resources, especially straw crop resources. The flourishing bio-chemical technology has been able to decompose the polysaccharides in corn stover. One of the ways is to refine fuel ethanol or polyols. One path is that after the poly-sugars have been acidified or esterified, they can partially replace petrochemical bitumen and reach the requirements for waterproofing membranes or road asphalt.

Changchun Dacheng Industrial Group has taken the lead in the development of plant-refined asphalt in China since 2010, and uses starch or C5 and C6 sugars in corn stover to convert into macromolecules after esterification or cyclization into macromolecular compounds. , reduce the amount of asphalt, to achieve partial replacement purposes. In the multiple tests of waterproofing membranes, according to the requirements of the effect, 5 to 15% of petrochemical asphalt can be replaced.

Compared with the extraction of vegetable oil feet, the renewable bitumen refined by the bio-chemical process has the requirements of industrialized large-scale production. According to our calculations, the useful C5 and C6 sugars of corn stalks account for about 60% of their mass proportion. It can be directly refined into high value-added fuel ethanol or polyol, and the remaining 30% can be directly refined into vegetable asphalt, equivalent to 18% per ton of corn straw can be made into vegetable asphalt.

It is conservatively estimated that the output of corn stalks in China's corn province Jilin Province alone is about 36 million tons. At present, most of the local farmers burn ash directly as fertilizers, resulting in a lot of waste and carbon dioxide emissions and polluting the environment. If half of the stalks can be effectively used to extract vegetable asphalt, an annual production capacity of approximately 3.24 million tons can be formed, which is close to the total amount of petrochemical asphalt that China needs to import from abroad. It is of great strategic importance.

Judging from economic returns, at present, the purchase price of corn stalks in Jilin Province is 400 yuan/ton, and the comprehensive utilization value accounts for 60%. Among them, the proportion of refining fuel ethanol or polyol is 42%, the average selling price in the market is 8,000 yuan/ton, and the remaining 18% can be made into vegetable asphalt. Assuming that the price of plant asphalt is 3,000 yuan/ton, then the total price per ton The product value can reach 3,684 yuan, the ratio of product value to raw material cost is 9.21:1, and there is a huge room for value improvement. Therefore, corn straw has considerable development and utilization value. At present, the technology of straw fuel ethanol or polyol has been very mature, and the development and utilization of plant refined asphalt is also just around the corner.

Fourth, innovative products require innovative application thinking

If we only rely on the comprehensive development and utilization of the plant oil foot, it is difficult to meet the demand of China's petrochemical bitumen market because the cost of collecting is too high due to the small size and dispersion of the oil foot of individual processing enterprises. However, biochemical companies are currently booming and growing in size. Especially with the comprehensive utilization and development of plant stalks, large scale production and production capacity can be achieved to meet the market demand for petrochemical asphalt. Plant asphalt can be used as a good molding adhesive in addition to applications in the field of paving and waterproofing membranes.

Plant asphalt does not belong to complex compounds of polyaromatic rings. It has the advantages of low-carbon environmental protection and renewable. After the petrochemical asphalt is depleted in the future, we can still produce a steady stream of plant refining technology. In addition, there is a clear difference with petrochemical asphalt, plant asphalt has a certain degree of hydrophilicity and degradability, can not simply give alternative use, must use some surface active solvents or emulsifiers in combination to improve compatibility with petrochemical asphalt .

Plant asphalt has good fluidity at room temperature, and evenly mixed with petrochemical asphalt, it will have a certain thickening effect. It will increase the adhesion and affinity of bitumen and calcium carbonate or stone, and it is not easy to appear sedimentation and stratification. Uniform.

Environmental consultants at the British Transport Research Laboratory believe that if plant asphalt is improved to the level of petrochemical asphalt in terms of recycling and durability, plant asphalt will have broad prospects for development.