**5. Conclusion**

Throughout this work, it has been shown that biogas is a very interesting source of renewable energy. Because of its elevated CH4 content, biogas has excellent potential, as reflected in its year-over-year rise in production. This is because its manufacturing promotes the use of organic waste, prevents uncontrolled dumping and minimizes atmospheric CH4 and CO2 emissions. In addition, its use as an energy source is in some cases an alternative to fossil fuels and can help to minimize energy dependence. Another aspect of interest is that it can be used insitu, allowing agro-livestock farms or small industrial plants to achieve energy self-sufficiency. A lot of studies on DRM over Ni-based catalysts has been carried out in latest decades to better comprehend the mechanism and techniques of response to improve carbon deposition resistance. Several methods were suggested to minimize the trend of Ni-based catalyst coke formation. One is the use of the appropriate catalyst preparation technique. Another is the use of metal oxides with strong Lewis basicity as supports or promoters (since Lewis acidity is identified to encourage coke buildup). Future study in this area is likely to focus on the use of catalysts based on bimetallic nickel, such as the incorporation of Co with Ni catalyst.

The bimetallic catalysts showed stable activity and elevated inactivation resistance, although carbon deposition occurs. Catalyst activity should be considered, as the primary reason for catalytic inactivation is the encapsulating carbon, which is deposited directly in the catalyst's active places instead of the carrier's surface. Also, when it is generated in large quantities, it can cause clogging of the reactor. The problem of carbon formation is exacerbated when biogas is used for this process, because the CH4:CO2 ratio of biogas is greater than that which can lead to the formation of large carbon deposits in a short time. However, carbon atoms are more essential in type and place than the quantity of carbon generated. Averting the

deposition of carbon is therefore a challenging task. Also, this problem can be addressed from a completely different perspective. Rather than trying to avert carbon formation, it can be promoted as carbon filamentous. Previously, many researchers have effectively accomplished the synthesis of carbon filamentous thru electric arc-discharge and laser ablation and chemical vapor deposition techniques. Nevertheless, the cost-efficient and the controlled synthesis of carbon filamentous with varies morphologies by those techniques has not been reported.

Given the broad range of applications and the growing demand for biogas in different areas, the superb characteristics of biogas indicate its growing potential as a source of syngas for a broad range of renewable energies, where high purity and low manufacturing costs are significant factors. Thus, producing high-purity syngas and the controlled production of value-added carbon filamentous over cheap, efficient, tunable and simply synthesized catalysts is very important and is the main interest in this subject.
